US President Barack Obama has swept to a second term, creating history again by defying the undertow of a slow economic recovery and high unemployment to beat Republican foe Mitt Romney.
Obama became only the second Democrat to win a second four-year White House term since World War II, when television networks projected he would win the bellwether state of Ohio where he had staged a pitched battle with Romney.
“In this election, you, the American people, reminded us that while our road has been hard, while our journey has been long, we have picked ourselves up, we have fought our way back,” Obama said at a triumphant victory party in Chicago.
“We know in our hearts that for the United States of America the best is yet to come,” Obama said..
As Obama’s victory was confirmed with wins in rustbelt Ohio and his spiritual political home in Iowa, large crowds suddenly materialised at the White House, chanting “four more years” and “O-bama, O-bama.”
Republican nominee Romney, deflated and exhausted, offered Obama a classy tribute, as he appeared before dejected supporters in Boston, moments after phoning the US leader to formally concede and to congratulate his team.
“I wish all of them well but particularly the president, the First Lady and their daughters,” Romney said.
“This is a time of great challenges for America and I pray that the president will be successful in guiding our nation.”
Obama repaid the compliment in his speech, saying the Romney family “had chosen to give back to America through public service and that is the legacy that we honour and applaud tonight”.
And in an intriguing aside, the president said he looked forward to sitting down with his former foe to find if they could find common ground to work together.
“This happened because of you. Thank you,” Obama tweeted to his 22 million followers on Twitter as a flurry of states, including Iowa, which nurtured his unlikely White House dreams suddenly tipped into his column.
With a clutch of swing states, including Florida and Virginia still to be declared, Obama already had 275 electoral votes, more than the 270 needed for the White House and looked set for a comfortable victory.
There was a sudden explosion of jubilation at Obama's Chicago victory party as the first African American president, who was elected on a wave of hope and euphoria four years ago, booked another four years in the White House.
Romney's aides had predicted that a late Romney wave would sweep Obama from office after a single term haunted by a sluggish recovery from the worst economic crisis since the 1930s Great Depression and high unemployment.
Romney told his supporters in Boston: “I have just called President Obama to congratulate him on his victory.”
The losing Republican nominee said Obama faced major challenges.
A huge cheer rang out at Obama headquarters when television networks projected Obama would retain Pennsylvania and its 20 electoral votes, and the party grew wilder as they called Wisconsin and Michigan.
The mood at Romney headquarters in Boston, however, had grown subdued throughout the evening as partisans stared at their smartphones.
Disappointed Republicans were seen leaving what had been billed as a celebration of Romney's expected triumph in central Washington.
Defeats in New Hampshire, where Romney has a summer home and Wisconsin, the home of Republican vice presidential nominee Paul Ryan, were especially sickening for Republicans.
Early signs were that the election, while a building triumph for Obama would do little to ease the deep polarisation afflicting US politics, as Republicans racked up huge margins in safe states, though struggled in battlegrounds.
Exit polls appeared to vindicate the vision of the race offered by Obama's campaign, when top aides predicted that Obama's armies of African American, Latinos and young voters would come out in droves.
Polls also showed that though only 39 per cent of people believed that the economy was improving, around half of Americans blamed President George W. Bush for the tenuous situation, and not Obama.
The president, who made history by becoming America's first black president after a euphoric victory, carved a new precedent on Tuesday by defying the portents of a hurting economy to win a second term.
He awaited his fate in his hometown of Chicago, while Romney, a multimillionaire former investment manager and Massachusetts governor was laying low in a hotel in Boston awaiting results.
CBS News, quoting early exit polls, said 39 per cent of people approached after they had voted said the economy, the key issue, was improving, while 31 per cent said it was worse and 28 saw it as staying the same.
Voters were also choosing a third of the Democratic-led Senate and the entire Republican-run House of Representatives. But, with neither chamber expected to change hands, the current political gridlock will likely continue.
The US presidential election is not directly decided by the popular vote, but requires candidates to pile up a majority - 270 - of 538 electoral votes awarded state-by-state on the basis of population.
A candidate can therefore win the nationwide popular vote and still be deprived of the presidency by falling short in the Electoral College.