While he has finally accepted the start of a transition process to the new administration, he has not conceded the election to Democratic candidate Joe Biden and is continuing his legal challenges to the results in some states.

Trump's insistence that the election was stolen from him is widely understood as baseless and an attack on the legitimacy of Biden's win and of American democratic institutions.

Given the facts about the election are so clear, why have so few Republicans acknowledged that Biden will be the next president of the United States? Why is it that only a handful of Republicans have called upon Trump - now a lame duck president - to accede to the conventions of a presidential transition, and cease his baseless attacks on the legitimacy of America's democratic institutions?

The answer is because of Trump's deep connection to the Republican base, still fervently in his corner.

Survey research by the United States Studies Centre, collected in the weeks before the election, found that Americans were deeply divided about the integrity of the 2020 election and accepting its outcome even before the count, with supporters of President Trump much more likely to report concerns about election fraud than Biden supporters.

We asked our sample of 1500 American respondents how often they thought mail-in ballots would be cast fraudulently, how often voters would be threatened with violence at the polls and how often they thought votes would be counted fairly.

Seventy-one per cent of Trump voters said they believed mail-in ballot fraud happened very or fairly often, and 30 per cent said votes would not be counted fairly. Just 13 per cent of respondents voting for Joe Biden thought mail-in ballot fraud happened often, and the same number thought they would not be counted fairly.

Pre-election, the Republican base had already accepted Trump's assessment that his loss would constitute evidence of election fraud. Safe for some quickly corrected rhetorical missteps, Trump hews to this line. With few Republicans challenging Trump's view, rank-and-file Republicans have little reason to think differently.

That Trump can sustain this argument, with little or no public opposition from Republicans, speaks volumes about his power.

For presidents losing re-election, authority drains away quickly, if it has not already prior to the election: think George H. W. Bush, Jimmy Carter, Gerald Ford or Herbert Hoover. But not Trump. He holds immense power over the Republican Party. Heading into the election, Trump's approval rating among Republicans was 95 per cent - a level of support rivalled only by the in-party ratings for Reagan and George W. Bush immediately before being re-elected.

The fact that Trump again "beat the polls" further cements Trump's status with the Republican rank-and-file. Any Republican thinking about criticising Trump will be reminded of his power to mobilise Republican primary voters and destroy the political careers of Republican dissenters.

Many states have certified their results, and legal and constitutional milestones for confirming the election results are fast approaching. States must lock in their slates of Electoral College electors by December 8, making Biden's win safe from legal challenge. Why risk Trump's wrath in the meantime?

Moreover, majority control of the US Senate is on the line, with the run-off elections for Georgia's two Senate seats on January 5. Trump may not be on the balot, but his power with the Republican base - and a narrative about "righting the wrong" of his loss" - will be a powerful message in that campaign. Few Republicans have an interest in running arguments contrary to that message.

But Trump's insistence that the election has been stolen is not just about the next three weeks. Rather, Trump seems intent on delegitimating Biden's win, emboldening Republicans to oppose Biden.

That is, right before the election many Republican voters were willing to believe the claims Donald Trump has been making about ballot fraud and irregularities with the counting of votes.

This concern about electoral integrity extended to an unwillingness to accept the outcome of the election. Just 45 per cent of respondents supporting Donald Trump agreed that "Joe Biden should be accepted as president if he wins the election".

This is not just a Republican thing, though. Only 31 per cent of Biden supporters agreed or strongly agreed that Trump should be accepted if he wins.

That is, clear majorities of the supporters of either presidential candidate endorsed not accepting the election winner as president, should the winner not be their preferred candidate.

This unwillingness to accept the candidate of the other party as the legitimate winner is likely in part a result of intense partisanship in the United States, increasingly associated with projecting negative views and stereotypes onto partisans of the other side.

This type of "negative partisanship" is apparent in views that Biden and Trump supporters have about whether each group of opposing partisans would accept a win by their preferred candidate.

Seventy-three per cent of Trump supporters said that Biden supporters would not support Trump should he win. Among Biden supporters, only 40 per cent said that Trump supporters would not accept a Biden win, with another 35 per cent saying they were unsure what Trump supporters would do.

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A number of theories are consistent with these findings. Trump voters may really think worse of Biden voters than Biden voters think of Trump voters. Or Trump voters can read the polls as well as anyone, and could see that a Trump win would be more of an upset than a Biden win, and that Biden supporters would be unlikely to accept a second Trump term.

But no matter the explanation, the fact that so few partisans think the "other side" is prepared to accept an election loss is concerning, and yet another signal of the deep divisions in American politics.

While violence on the day of the election was very low, there is no shortage of anecdotal evidence of Americans bracing for unrest immediately prior: including spikes in gun sales, retailers boarding up storefronts before the election, fearing unrest, and a Biden campaign bus being harassed by Trump supporters in Texas.

Our data points to deep levels of suspicion and mistrust across party lines in the United States around the election result. This presents something of a tinderbox, which President Trump appears willing to ignite in his refusal to accept the results.

Although the process is slowly being resolved, the messages Donald Trump and the Republican leadership send to their followers over the following days and weeks will help determine how much lasting damage is done to America's political institutions.