Barack Obama has been re-elected as President of the United States.
Voting was close in the race for the White House with Republican challenger Mitt Romney needing to win key swinging states.
However all major television networks in the US have predicted an Obama victory.
With 270 needed for victory the current numbers are 303 to Mitt Romney's 203.
All times AEDT
5:40pm: Barack Obama addresses supporters and have thanked the American people. "You, the American people, reminded us that while our road has been hard we have picked ourselves up."
5:35pm: US President-elect Barack Obama has claimed victory in the US Election and is thanking his supporters. His wife Michelle and children have walked out on stage with him.
5:20pm: The crowd in the Chicago convention centre is now at near fever pitch anticipating the arrival of Barack Obama.
5:15pm: Australian Prime Minister Julia Gillard has congratulated Barack Obama on his victory.
"On behalf of the Government and people of Australia, I offer warm congratulations to President Barack Obama on his re-election and wish him every success for his second term in office.
"Our Governments and countries share a similar outlook on the world and similar hopes and aspirations for our peoples.
"Australia has a long history of working with the United States to make a difference on these global challenges."
5:08pm: Now we stand by for Barack Obama to claim victory.
5:02pm: Romney on Obama: "Ann and I join with you to earnestly pray for him and this great nation."
5:01pm: Romney to supporters: "I so wish that I had been able to fulfil your hopes to lead this country in a different direction."
4:55pm: Mitt Romney addresses supporters to concede defeat in the US Presidential Election.
4:50pm: There are reports Republican Mitt Romney has called US President-elect Barack Obama to concede defeat.
4:42pm: Obama now takes lead in popular vote by about 28,000 votes.
4:32pm: Former foreign minister Alexander Downer told the ABC the Tea Party had a lot to answer for.
"I think for me the really interesting thing is that within the Republican Party, they're going to have to resolve the tension between the mainstream traditional Republicans, sometimes referred to as the Republican establishment, and the Tea Party people.
"My guess is - I might be wrong about this and this might be a bit more wishful thinking on my part - but my guess is that Republicans generally will realise that the Tea Party campaign has really wrecked their chances of turning Barack Obama into a one-term president, not Mitt Romney."
4:28pm: There is nothing in the popular vote as Obama continues to close the gap. With around 73 per cent counted nationally, Romney leads Obama 49,028,980 to 49,028,645 - a lead of just 335 votes.
4:23pm: Another tweet from president
We're all in this together. That's how we campaigned, and that's who we are. Thank you. -bo
4:20pm: US stock futures and the greenback fell as television networks projected Barack Obama's re-election, signalling no dramatic shift in US economic policy.
4:18pm: There were a lot of other issues decided on election day in the US.
Among them was the state of Maine becoming the first to have gay marriage delivered through popular vote.
4:06pm: The New York Times calls the battleground state of Virginia for Obama.
If it wasn't over before... it surely is now.
4:03pm: Some Republicans are refusing to give up.
George W Bush adviser Karl Rove is on Fox News and appears to be urging them to rescind their decision to call Ohio for Obama, and therefore their presidency.
4:02pm: We are awaiting the speeches from Barack Obama and Mitt Romney. With the Romney camp not willing to yet concede defeat it might be a while. Watch 7News coverage above.
3:58pm: Donald Trump is not a happy camper.
3:40pm: CNN reports Mitt Romney is not yet ready to concede.
3:26pm: Obama picked up the swing states of New Hampshire, Michigan, New Mexico, Iowa, Wisconsin, Pennsylvania, Minnesota, and Ohio. Florida and Virginia are still too close to call, but even if he won them, they would not give Romney enough Electoral College votes to put him over the top. Romney looks poised to do better in the overall popular vote.
3:17pm: NBC calls the election for Barack Obama
3:06pm: CNN projection: Obama 249, Romney 191 with 270 needed for victory.
3:04pm: Obama takes California, Hawaii and Oregon. Romney takes Idaho and North Carolina which is an important swing state. Ohio, Florida, Virginia and Nevada are all too close to call.
2:55pm: Obama is still ahead in Florida with 92 per cent of precincts counted.
2:41pm: The numbers are Obama 227, Romney 178 with 270 needed to win.
2:36pm: How can Romney win from here? ABC election expert Antony Green says that "Beyond 191 [Electoral College votes] they need to win Florida, North Carolina, Virginia and Ohio and another state. We've just given Wisconsin away, so the numbers are getting much, much tighter. We started this coverage several hours ago and we're waiting on Virginia, North Carolina and Florida."
2:32pm: Although he leads in the Electoral College, Obama trails on the raw numbers of votes counted nationally. He has 48.1 per cent against Romney's 50.6 per cent.
2:22pm: The US networks have called the following states:
Romney: Louisiana, Montana, Alabama, Arkansas, Georgia, Indiana, Kansas, Kentucky, Mississippi, Oklahoma, South Carolina, Tennessee, West Virginia, North Dakota, South Dakota, Nebraska, Texas, Utah, Wyoming.
Obama: Pennsylvania, New Hampshire, Michigan, New York, Wisconsin, Connecticut, District of Columbia, Delaware, Illinois, Massachusetts, Maryland, Maine, New Jersey, Rhode Island, Vermont.
2:11pm: President Barack Obama has won the battleground state of Wisconsin, depriving Mitt Romney of a key target that could help him win the White House.
2:00pm: US network CNN is reporting that it is virtually impossible for the Republicans to regain control of the Senate.
1:53pm: The Republicans look like holding the balance of power in the House of Representatives. Mitt Romney also has a narrow election lead.
1:38pm: Florida, Ohio and Virginia are too close to call. Obama is projected to win Pennsylvania, Michigan and Wisconsin. They are neck-and-neck in Florida, which Obama can afford to lose but Romney must win. Romney must win Ohio to keep his chances alive.
1:33pm: Fox and NBC are giving Wisconsin to Obama. That's Romney's running mate Paul Ryan's home state.
1:32pm: US networks are predicting the Republicans will have control of the House of Representatives. Not unexpected, but it would make life difficult for Obama if he gets back in.
1:13pm: Barack Obama and Mitt Romney have grabbed states traditionally loyal to their parties but swing states Virginia, Florida and Ohio are too close to call.
1:06pm: Exit polls have Colorado too close to call, with each candidate on 48 per cent. US networks are starting to call for Michigan - ABC, CBS, CNN and Fox News all declaring for Obama.
1:03pm: CNN predicts Romney to win Texas, Kansas, Louisiana, Nebraska, North Dakota. The network gives Michigan, New York and New Jersey to Obama. More exit polls coming soon.
12:40pm: Colorado and Wisconsin will close at 1:00pm AEDT.
12:32pm: Obama is leading 58 per cent to 40 per cent in Ohio with 20 per cent of the vote in - but the booths which have reported are in Democratic areas.
Arkansas has just closed and it's in the bag for the Republicans.
12:29pm: Republican challenger Mitt Romney has won Indiana, a state won by President Barack Obama four years ago.
12:26pm: Ohio, Virginia and Florida are all still too close to call.
12:18pm: The US networks have called the following states:
Romney: Alabama, Georgia, Indiana, Kentucky, Mississippi, Alabama, Oklahoma, South Carolina, Tennessee, West Virginia.
Obama: Connecticut, District of Columbia, Delaware, Illinois, Massachusetts, Maryland, Maine, New Jersey, Rhode Island, Vermont.
12:16pm: Reporters are gathering in Chicago ahead of Obama's rally later today. The mood in Obama HQ is reported to be tense.
12:15pm: Mitt Romney told reporters on his jet that his team will be successful because they've "put it all on the field, left nothing in the locker room"
11:56am: John Barron says exit polls show 79 per cent of voters in Ohio today are white, down 5 per cent on four years ago.
"That's generally good news for down Barack Obama," he says.
"They've also said by a margin of 56 per cent to 44 per cent that [Obama's] auto bailout was a good thing."
11:52am: People in Queens, still without power after Sandy, listen to the election news on the radio.
11:50am: The rest of Florida; Pennsylvania; and New Hampshire will all close at the top of the hour.
11:49am: Lisa Millar reports from Romney's HQ in Boston and she says confidence is high in the Republican camp as the results start to trickle in.
"[Romney's] written a victory speech, 1000 words and clearly he's not planning to do anything other than be having a party here this evening in the Convention Centre behind me," she said.
"Bus loads of people are you turning up. They're looking and feeling pretty confident, walking in cheering. There were school children, high school children, who have turned up who have been volunteering and helping getting people to the polls here in Massachusetts.
"Certainly, nothing but confidence in Boston from the Romney camp, but as those figures keep coming in, we'll see whether that confidence dies away as the Obama camp suggests it will."
11:45am: So far the US networks have called Indiana, Kentucky, South Carolina and West Virginia for Romney; and Vermont for Obama. All as expected.
11:35am: Florida is on two time zones. The last polls there close at midday AEDT. But with 23 per cent of the vote counted, CNN says the state is running 52 per cent to 48 per cent in Obama's favour.
11:32am: CNN exit poll has Obama leading 51 per cent to 48 per cent in must-win Ohio.
11:31am: CNN is giving West Virginia to Romney but says Ohio and North Carolina are too close to call.
11:30am: Voting has closed in Ohio, West Virginia and North Carolina.
ABC election expert Antony Green says Florida is running 50.2 per cent to Romney, 49.2 per cent to Obama, but it's very early in the count.
11:25am: Professor Stephen Farnsworth, of the University of Mary Washington, talks about the states upon which the US presidency hinges as the first polls close.
11:21am: With 5 per cent of the vote counted in Florida, the result is 50-50, according to CNN.
11:17am: The next big results are due around 11:30am when the key swing states of Ohio, West Virginia and North Carolina close.
Keep an eye on Ohio, Wisconsin and Iowa, the states which have been dubbed Obama's "mid-west firewall". If the firewall holds for Obama, Romney's path to the White House is very, very difficult.
11:12am: Reuters/IPSOS exit poll says first-time voters broke two-to-one for Obama nationally.
11:10am: Romney is leading exit polls in Indiana and Kentucky; the US networks give Vermont to Obama.
11:05am: Electoral votes are being allocated according to ABC election analyst Antony Green's call of the states.
11:04am: On a knife-edge: CNN exit poll in Virginia shows 49 per cent to Obama, and 49 per cent to Romney.
11:03am: An early boost for Obama? John Barron says CNN's Peter Hamby reports that a source in the Romney camp has told him that internal Republican polling over the weekend has Obama 5 per cent up in must-win Ohio.
"If that's the fact ...that is very good news for Barack Obama," Barron says.
11:00am: The polls have closed in the key state of Virginia.
ABC election analyst Antony Green has already called it in a swag of states which he says can be predicted ahead of time.
He says his tally gives Obama 177 Electoral College votes against 167 for Romney.
10:45am: 15 minutes to go until Virginia closes. The ABC's Jane Cowan says many analysts are pointing to a long night ahead, but she has given some tips for predicting the outcome as the polls close:
"Things to look for are what happens in Virginia. That's a must-win state for Mitt Romney where the polls will be among the first to close," she said.
"If the president for instance wins Virginia, Mitt Romney would virtually have to sweep the board of the remaining contested states to pull off a win.
"Equally if Mitt Romney wins Ohio people should settle in for a long night because that could signal that this much-hyped ground organisation of the Obama campaign is faltering."
10:40am: Barack Obama is out in front in American 7-Eleven stores, where an unofficial poll is being conducted based on purchases of coffee.
Shoppers are invited to get a "steaming hot cup of democracy" by choosing from either a blue Obama cup or a red Romney cup when they buy a coffee.
This morning Mr Obama is comfortably sitting on 59 per cent, while Mr Romney is on 41 per cent.
ABC US election analyst John Barron says Obama has the advantage.
"The latest opinion polls suggest Barack Obama still has his nose in front in the Electoral College.
"If we assume Mitt Romney is going to win Virginia and Colorado, where Barack Obama is less than 1 per cent in favour, Obama will win 181 [Electoral College votes], 11 more than he needs.
"But that also means if Ohio or Pennsylvania is able to flip into Mitt Romney's column he will be president-elect of the United States before we finish today. That could still happen."
10:20am: After Virginia closes at 11am, the next states to close will be Ohio and North Carolina at 11:30am.
10:16am: The polls have closed in most of Indiana and the eastern part of Kentucky.
Polls closed at 10am AEDT in parts of the two states observing Eastern Standard Time. The states both straddle two time zones.
10:02am: Now less than an hour until the polls close in Virginia.
9:58am: Michael Rowland says the polls are putting Barack Obama ahead with 290 electoral college votes. But George W Bush's former strategist Karl Rove has predicted Mr Romney will get 285 electoral college votes.
"Republicans are telling us that these polls are all wrong, they're skewed towards the Democrats, the mechanisms used by pollsters are completely wrong," Rowland said.
"Their internal polling shows them that Mitt Romney has a much, much stronger chance than the public polls are showing."
Candidates need at least 270 votes to win.
Donald Betts, a former Democratic senator from Kansas, has told the ABC that Americans feel there is a lot at stake in this year's election.
"Previous years the [voter] numbers have been lower because it hasn't been such a dramatic election," he said.
"In this case it's life or death. In some American's eyes this is the election. I mean it's the election for the future of our families and our children."
The Pew Research Centre has surveyed Hispanic voters in the US. They say there are a record 24 million Latinos eligible to vote and of those likely to vote, 66 per cent are set to back Obama, to 27 per cent Romney.
9:33am: Locals in the small Kenyan village where Barack Obama's late father grew up have held a mock US election.
But one Kenyan voter is bad news for Mr Obama. He says Mitt Romney came to him in a dream last night so he now expects the Republican to win.
9:28am: Lisa Millar fills us in on some "inconsequential information that no one really needs to know" from Team Romney:
"In Ohio he had a burger and a frosty and we don't know if it was chocolate or vanilla," she said.
"But that's the kind of details that are currently being put out by the reporters who have faithfully for 18 months covered every single move of Mitt Romney."
Meanwhile Barack Obama is reported to be playing basketball with former members of the Chicago Bulls in Chicago.
9:16am: New York Times election analyst Nate Silver puts Barack Obama's chances of winning today's election at higher than 90 per cent, saying the incumbent has in the final days of the campaign.
Silver, during the campaign, says a large number of polls across multiple states would have to be in error for Mitt Romney to win.
9:12am: Republican strategist Liz Meagher is speaking to Michael Rowland on ABC News Breakfast.
She says "Republicans are optimistic, they feel they've made significant gains", and Pennsylvania is still in play.'
"They're also seeing with regard to Pennsylvania, in the western part of that state, there's a lot more enthusiasm for Mitt Romney than what they expected.
"And even Obama's deputy campaign manager Stephanie Cutter said if if she were in the Romney camp's position she would be making a play for Pennsylvania on that basis also.
"We're cautiously optimistic. I don't think anybody thinks we've got this in the bag, but a lot of folks who are handling turnout operations feel that they are going to be capable to do enough to just push over the finish line."
8:56am: From the photo desk: Members of the National Guard deployed on the Hurricane Sandy clean-up in New Jersey cast absentee votes:
8:50am: Mitt Romney took his campaign right down to the wire overnight, squeezing in visits to Ohio and Pennsylvania as voters headed to the polls. Here he thanks his supporters during a last-minute appearance in Ohio, saying "it is a big day for big change".
8:38am: Democrat strategist Linda Moore-Forbes has told the ABC's Michael Rowland that Team Obama is confident.
"Feeling really good. The turnout seems really strong. What I'm definitely picking up is a strong turnout among young people," she said.
She says Mr Obama isn't campaigning today because it's a drain on resources.
And she says Mitt Romney's appearance in Pennsylvania today is more likely to energise Democrats than help the Republican campaign.
8:23am: In Dixville Notch, New Hampshire, the 10 eligible voters in town have the honour of being the first in America to have their ballots counted.
When the results came in overnight they had tied, with five residents backing Barack Obama and five behind Mitt Romney.
8:05am: Here's the state of play so far this morning: There are reports of long queues at polling booths across the US, and hopes voter turnout could be as high as 58 per cent. Obama has visited his campaign HQ in Chicago and thanked the volunteers who have worked for him. Romney squeezed in two last-minute campaign stops in Pennsylvania and Ohio. The first results have been tallied in Dixville Notch, where Obama and Romney tied on five votes. Results are also in from Hart's Location where Obama had 23 votes to nine for Romney.
7:53am: Leading US pollster John Zogby tells Michael Rowland that he expects Barack Obama to be re-elected as president with 290 Electoral College votes.
7:43am: Greeted with loud cheers of "Romney! Romney!" and "We love you Mitt!", Mitt Romney sounded confident as he thanked volunteers helping his campaign:
"Thank you so very much for being here today. It's critical because it is a big day for big change," he said.
"The country's been going in the wrong direction for the last few years and we're going to steer it back.
"I'm so excited about the prospects."
7:32am: There are still reports of long queues at polling booths across the US and there are hopes voter turnout could be as high as 58 per cent.
7:07am: The New York Post has endorsed Republican Mitt Romney.
The Rupert Murdoch-owned paper said Americans today have to make a fateful choice:
"Will they continue down the path to terminal indebtedness and endless economic decay - or will they try something different, something more hopeful?
Will they vote for Mitt Romney? We hope so."
7:00am: Mitt Romney has arrived in the swing state of Pennsylvania for more last-minute campaigning.
He is due to hold a rally in Pittsburgh shortly.
Meanwhile, analysts still say the vote is too close to call.
While it's raining in Barack Obama's hometown of Chicago, Millar says Boston's weather is giving them a run for their money, with temperatures close to freezing.
6:35am: Mr Obama has thanked Mitt Romney for running a "spirited campaign".
"I want to congratulate Governor Romney and his team for a hard fought race as well."
6:29am: Barack Obama visits his campaign HQ in Chicago and thanks the volunteers who have worked for him.
"It's a source of great optimism for me whenever I come to election day because I end up having so much confidence in the decency and goodness and wisdom of ordinary folks who are working so hard trying to move their own small piece of this country forward," he said.
6:20am: OVERNIGHT RECAP: The first results have been tallied in Dixville Notch, where Obama and Romney tied on five votes. Results are in from Hart's Location where Obama had 23 votes to nine for Romney. Both candidates have now cast their votes. Obama is spending the day in his hometown Chicago, where he has visited his campaign office. Romney is doing last-minute campaigning in swing states Pennsylvania and Ohio.
6:13am: Polls show Barack Obama has a slight advantage in several of the vital swing states - most notably Ohio.
5:55am: Apparently things got a little awkward at the Cleveland airport; Mitt Romney landed first, but when Joe Biden swooped in on Air Force Two the Republican was forced to wait on the tarmac until Mr Biden's motorcade had left.
Minutes later the tarmac became even more crowded when Republican vice presidential candidate Paul Ryan flew in.
5:48am: Republican challenger Mitt Romney and US vice president Joe Biden are both doing some last minute campaigning in Ohio.
In fact, the planes of both men are currently sitting on the same tarmac at Cleveland airport.
5:39am: NEWS JUST IN which may compound fears of a low voter turnout in areas battered by last week's hurricane, New York mayor Michael Bloomberg is now asking residents of some low-lying areas to evacuate by Wednesday (US time) ahead of another storm. NYC parks will also be closed.
5:27am: See what time polling booths close this morning in the battleground states:
Opinion polls show Obama and Romney in a virtual dead heat, although the Democratic incumbent has a slight advantage in several vital swing states that could give him the 270 electoral votes needed to win the state-by-state contest.
Traditionally presidential candidates get media attention on Election Day by going to vote. But Obama cast his ballot in Chicago last month - part of his campaign's push to get its supporters to vote early.
Obama and Romney, a former Massachusetts governor and private equity executive, have fought a largely negative campaign. Obama's team attacked Romney for his business record, and Romney's team criticized the president for presiding over high unemployment and a slow economic recovery.
Obama's conciliatory comments represent the close of the bitter campaign and could appeal to last-minute undecided voters, who are turned off by the lack of bipartisanship in Washington.
In addition to his campaign office stop, Obama is doing a round of interviews and is expected to play basketball with friends, a tradition for the sports-loving president on Election Day.
Obama, Romney tied in Dixville Notch
Dylan Stableford, Yahoo! News | The Ticket
The first results of the 2012 election are in, and President Barack Obama and Mitt Romney are tied.
As has been the tradition since 1960, residents of Dixville Notch, a tiny village in Coos County, New Hampshire, cast their ballots - all 10 of them - shortly after midnight Tuesday. The vote took just 43 seconds, with five counted for the president, and five for the Republican challenger.
According to the town clerk, there are just two registered Democrats, three Republicans and five independents. According to U.S. Census data, the town had a population of 12 in 2010.
It's the first tie in Dixville Notch presidential voting history. In 2008, Obama collected 15 of the 21 votes cast - the first time in 40 years Dixville voted Democratic - with Sen. John McCain grabbing the other six.
In 2000 and 2004, the village went to George W. Bush.
Nearby Hart's Location, N.H., which began a similar early voting tradition in 1996, released their own results early Tuesday: Obama received 23, while Romney tallied 9. Third-party candidate Gary Johnson grabbed two.
According to the latest University of New Hampshire/WMUR poll conducted Nov.1-4, Obama leads Romney 51 percent to 48 percent among likely Granite State voters.
Two final tracking polls split between Obama and Romney
Liz Goodwin, Yahoo! News | The Ticket
Two final tracking polls from Gallup and the Washington Post/ABC News were released Monday, with the former showing Mitt Romney up 1 point among likely voters and the latter favoring President Obama by 3 points.
Gallup says Romney leads Obama by 1 point among likely voters, 49 to 48 percent. The poll's margin of error is 2 percentage points, meaning the race is a statistical tie. (Three percent of likely voters told Gallup they were undecided.)
The Washington Post/ABC News tracking poll has Obama at 50 percent and Romney at 47 percent among likely voters. The poll has a margin of error of 2.5 percentage points, which means a small portion of the president's lead is statistically significant.
The poll also found that 55 percent of likely voters believe Obama will win the election.