Can Donald Trump block Joe Biden's victory?

Since US media declared Joe Biden's White House victory on Saturday, President Donald Trump has refused to concede and repeatedly made baseless claims of election fraud.

Trump's team has mounted legal challenges in at least five key states yet experts see the possibility of the courts overturning the result of the vote as vanishingly small. And a manual recount ordered in Georgia is unlikely to overturn Biden's slim lead.

Here is an update nine days from Election Day on how long the vote can be disputed and whether Biden's victory is at risk:

Though US media projected Biden as the winner in key states like Pennsylvania, final votes were still being tallied.

At the same time, Georgia has already announced its ballots will be recounted by hand and a recount is also possible in Wisconsin.

However, each state has its deadline for officials to certify election results: Georgia has until November 20, Pennsylvania's is November 23 and in Arizona, it is November 30.

Read: Few legal wins so far as Donald Trump team hunts for proof of election fraud

"I actually don't think we're going to wait until all the states have formally certified," said John Fortier, election specialist at the Bipartisan Policy Center, an organization that aims to bridge the Republican-Democratic divide.

"As things move along in the counting and reconciling and perhaps as some of the challenges going forward are not working out or not changing many votes... the margins, even though close, will seem too big to be able to be changed by any sort of further legal action," he added.

Experts note that the real deadline is December 14, when the all-important Electoral College meets in each state to formally elect the president based in principle on the popular vote of each state.

That deadline was hit even in 2000 when George W. Bush beat Democrat Al Gore after five weeks of legal battles over recounts.

Trump's attacks on the election's integrity have raised the worry that the popular vote might not be honoured in the Electoral College.

One scenario involves states where the governor's office and legislature are held by rival parties, with each certifying their own opposing slate of electors.

"It is extremely unlikely, but it is worrisome that it's being discussed," said Barry Burden, a political scientist at the University of Wisconsin-Madison.

That scenario is a potential risk in battleground states like Michigan, Pennsylvania and Wisconsin, which the US media called for Biden but have Democratic governors and Republican-controlled legislatures.

Read: Will Joe Biden’s victory resuscitate liberalism?

In the case of dual slates, the election dispute would end up before the US Congress, which meets January 6 to tabulate Electoral College Votes and to formally designate the next president.

However, several key states would have to submit rival electoral votes in order to call Biden's victory into question, which experts interviewed by AFP considered out of the realm of possibility.

"Trump is likely to never accept his loss," said Burden. "He continues to complain about the 2016 election which he believes was rigged against him -- even though he won fair and square."

Biden would still be inaugurated as president on January 20, 2021, but the refusal to concede casts a cloud over the former vice president's victory.

"Just raising the question may be enough -- that maybe all the campaign is hoping to do," Burden added.

Fortier, the election specialist at the Bipartisan Policy Center, said: "I believe there will be a peaceful transition of power, absolutely."

"I'm not sure there is going to be lasting damage... and the presidency will proceed whether there is a friendly transition or not," he added.