Joe Biden's US election win marks a setback for Israeli premier Benjamin Netanyahu, a staunch ally of President Donald Trump -- but it could spur renewed engagement between Washington and the Palestinians, experts said.
Netanyahu called Trump Israel's strongest-ever ally in the White House, and the Republican advanced policies that delighted the Israeli prime minister's right-wing base.
Trump unilaterally pulled out of the 2015 Iran nuclear deal -- an agreement between Tehran and world powers loathed by Netanyahu -- and recognised Jerusalem as Israel's "undivided" capital.
He also endorsed Israeli sovereignty over the Golan Heights -- which was seized from Syria -- and avoided criticising Jewish settlements in the occupied West Bank.
According to a poll before the US election by the Israel Democracy Institute think-tank, 63 percent of Israelis wanted Trump to win a second term.
Biden is expected to reverse much of Trump's record.
The president-elect has said he opposes West Bank settlement construction, in line with an international consensus that Jewish communities in the occupied Palestinian territory violate international law.
But Biden's Israel ties run deep and, in keeping with decades of US policy, he has been a vocal supporter of the Jewish state.
He visited Israel in 1973, just months after he was first elected to the US Senate.
In a 2015 speech, while serving as Barack Obama's vice president, Biden said the United States was wedded to a "sacred promise to protect the homeland of the Jewish people".
During the 2012 vice-presidential debate, when Biden was facing criticism over the Obama administration's treatment of Israel from Republican Paul Ryan, Biden asserted that he and Netanyahu had "been friends for 39 years."
Israel's former envoy to Washington, Michael Oren, notes Biden does indeed have a "genuine friendship" with Netanyahu.
- Iran, normalisation deals -
However, Oren believes friction between Biden and Israel will spike if the new adminstration seeks to revive Obama's nuclear deal with Iran, a prospect he said had a "very high" likelihood.
"Netanyahu will be perceived as the person who failed to stop the Iran agreement -- in 2015 and in 2021," he told AFP in an interview on Thursday, referring to domestic perceptions of the Israeli premier.
Netanyahu, and much of Israel's security establishment, blasted the Iran deal, claiming it offered an arch-foe massive financial benefits while failing to eliminate the threat of a nuclear-armed Islamic republic.
Iran insists its nuclear programme is strictly for civilian purposes.
A Biden effort to revive the Iran pact could also affect Israel's Trump-brokered normalisation deals with the United Arab Emirates and Bahrain, said Eytan Gilboa, political science professor at Israel's Bar-Ilan University.
The Jewish state signed normalisation deals with these two Gulf states in September, on the lawn at the White House, spurring a raft of more detailed agreements.
The UAE, Bahrain and especially Saudi Arabia -- Sunni Muslim led states -- are bitter rivals of Shiite majority Iran.
Experts have said that the normalisation deals as well as warming ties between Israel and Saudi Arabia under Trump were partly driven by a desire to forge a united front against Iran.
"The Iranians are going to say you cannot have it both ways: you cannot have negotiation with us, and at the same time help to expand the coalition that is basically against us," Gilboa said.
- BDS -
Israeli officials are also concerned that the growing number of Israel critics in the Democratic Party will have influence over Biden's administration, Gilboa said.
Vermont Senator Bernie Sanders, tipped for a possible cabinet post, has called Netanyahu a "reactionary racist."
Israel has meanwhile accused two Democratic congresswomen, Rashida Tlaib and Ilhan Omar, of supporting the Boycott, Divestment and Sanctions movement against Israel over its treatment of the Palestinians.
According to Gilboa, "the progressive, radical branch of the Democratic party" is "anti-Israel" and gaining strength.
"We don't know yet how much influence they will have on policy making," he said.
- Initial Palestinian reactions -
Under Trump, relations between Washington and the Ramallah-based Palestinian Authority collapsed.
Trump cut funding to the UN agency responsible for Palestinian refugees (UNRWA) and rejected the notion that Israeli-annexed east Jerusalem should serve as the capital of a future Palestinian state, among other dramatic policy shifts.
Ismail Haniya -- head of Hamas, the Islamist group which controls the Gaza Strip --- on Saturday evening called on Biden to "correct" Trump's "unjust policies."
Meanwhile, Nabil Shaath, an adviser to Palestinian president Mahmud Abbas, called the end of Trump's presidency "a victory".
Trump's controversial Middle East peace plan was unveiled in January with no input from the Palestinians, who rejected it outright.
Experts agree that while a renewed Middle East peace push is unlikely to top Biden's immediate agenda, his administration will seek to restore America's traditional role as a broker in the Israeli-Palestinian conflict.
"It is likely that they will seek much more engagement" with the Palestinians, said Sarah Feuer of the Institute for National Security Studies in Tel Aviv.