Republican Donald Trump’s false claims of voter fraud in the critical battleground state of Pennsylvania have fueled concern that he may again try to overturn the election results if he fares poorly against Democrat Kamala Harris in Tuesday’s US presidential election.

Polls, both nationally and in the seven closely divided states, show former President Trump locked in a tight race with Vice President Harris four days before Election Day.

Trump continues to falsely claim that his 2020 loss to Democratic President Joe Biden was the result of widespread fraud in several states that Trump lost, while he and his supporters spread baseless claims about these elections.

Trump on Thursday stepped up his baseless accusations that investigations into suspected voter registration forms in Pennsylvania are evidence of voter fraud. Some of his supporters alleged voter suppression when long lines formed this week to receive mail-in ballots.

Harris’ Democrats, meanwhile, are bracing for the possibility that Trump might try to prematurely claim victory before the votes are counted, as he did in 2020. Their initial plan is to flood social media and the news media with calls to calmness and patience in case they do that.

“We are, unfortunately, prepared if he does, and if we know that he is actually manipulating the media and trying to manipulate the consensus of the American people … we are prepared to respond,” Harris said in an interview with ABC on Wednesday.

Trump’s false claims of voter fraud after the 2020 vote preceded the deadly January 6, 2021 attack on the US Capitol by Trump supporters seeking to stop or alter Congressional certification of electoral votes that determine who becomes president.

“This sows the seeds for attempts to overturn the election,” said Kyle Miller, a strategist with the advocacy group Protect Democracy. “We saw it in 2020, and I think the lesson that Trump and his allies have learned since then is that they have to sow these ideas early.”

Trump allies have also expressed concern that non-citizens could vote in significant numbers, though there are few examples of that.

On Friday, multiple US intelligence agencies said Russia created a video circulating online that falsely shows people from Haiti voting multiple times in the state of Georgia. The video is part of Russia’s efforts to undermine confidence in the election and divide Americans, the agencies said.

Georgia’s top election official said Thursday that the video likely came from a Russian troll farm.

State officials and democracy advocates said the incidents in Pennsylvania show a system working as intended. A judge extended the deadline for mail-in voting by three days in Bucks County, north of Philadelphia, after the former US president’s campaign sued alleging some voters were turned away before Tuesday’s deadline.

Election officials discovered potentially fraudulent registrations in Lancaster and neighboring York counties, prompting investigations by local law enforcement. There is no evidence that the requests led to illegal votes.

As the election nears, election officials are scrambling to dispel misinformation narratives about voter fraud.

In Pennsylvania’s Northampton County, an activist posted a video of someone dropping off a ballot bin at the county courthouse and said it was suspicious; turned out to be a US Postal Service worker “literally just delivering mail,” Pennsylvania Secretary of State Al Schmidt said.

The video has been viewed over five million times on X.

“I feel like what’s most different this year is the intentional spread of false information that spreads around the globe before we have a chance to learn the truth,” former Pennsylvania Secretary of State Kathy Boockvar said during a webinar about Friday.

PREPARING FOR A FRAUD LOSS

Trump held a rally in Michigan on Friday and was later scheduled to speak in Wisconsin, while Harris spoke in Janesville, Wisconsin, and was later to be in Milwaukee for a rally with rapper Cardi B.

Senior Harris campaign staff say their internal data shows Harris won the battleground state voters who decided last week by double-digit margins.

Trump’s New York rally on Sunday, which featured vulgar and racist remarks from allies, was the “last straw” for late-night undecided voters, according to a Harris campaign official.

Trump told his rallies to expect a big victory on Tuesday, saying he could only imagine losing “if there was a corrupt election.”

Trump’s claims raised concerns that he was preparing to again blame a potential loss in Pennsylvania, the largest of the seven states that could decide the outcome of the election, on voter fraud.

In a social media post Thursday, he said, “I caught them cheating in Pennsylvania,” and called for criminal charges.

The US’s unique method of electing a president, rooted in the Constitution adopted in 1789, gives Trump the opportunity to try to undermine election results at the local, state and national levels.

In 2020, the Trump team tried 60 court cases alleging fraud in multiple states, all without success. But the experience has prepared lawyers on both sides for another try this year.