"Rigged election!," Trump tweeted defiantly Thursday morning.
Election officials around the country have also denied the existence of widespread fraud and the president-elect, Joe Biden, leads Trump by some 5 million votes nationwide.
Here are five claims that have been widely pushed and debunked.
False claim: Ballots were counted, even though they arrived late.
Trump tweeted a viral video of ballots being collected from a drop box in Los Angeles on Nov. 4, the day after Election Day – without further explanation. "You are looking at BALLOTS! Is this what our Country has come to?," Trump asked, an apparent attempt to suggest the video showed something improper.
The video shows elections officials picking up ballots from a dropbox while being asked questions by the woman filming them. An L.A. County official confirmed to ABC News the ballots in the video “are valid ballots" that did not arrive late, despite the video's attempt to cast doubt on their legitimacy.
“All vote by mail ballot drop boxes were closed and locked at 8 PM on Election Day. Ballots from all boxes throughout the County were picked up the following day,” Los Angeles County Registrar told ABC News in a statement. "Additionally, the individuals in the video are Registrar staff."
In numerous lawsuits, the Trump campaign has claimed without proof that late-arriving ballots are being counted, an effort they say has given Biden a lead over Trump. There is no evidence late-arriving ballots are being counted. (And Biden leads in California by nearly 5 million votes.)
False claim: Military ballots went missing in Georgia?
In the days following the election last week, Trump posed a question on Twitter to his nearly 90 million followers: "Where are the missing military ballots in Georgia? What happened to them?"
No military ballots, or any ballots for that matter, were missing in Georgia, according to the Republican Secretary of State's office. Military ballots had until Friday, Nov. 6 at 5 p.m. to arrive at clerks' offices to be counted-- a deadline that had not yet passed when Trump sent that Tweet.
Gabriel Sterling, who helped with the election in Georgia in the secretary of state's office, at the time had said there were just over 8,000 military ballots still outstanding, which had been requested and not yet returned. He emphasized these are "not missing ballots."
“There’s ballots that are going to make it, there’s ballots that are not going to make it,” Sterling said. Biden led Trump by some 14,000 votes as of Nov. 12.
Unsupported claim: late ballots were backdated in an attempt to allow them to be counted.
In a lawsuit in Michigan seeking to halt ballot counting in the state, the Trump campaign provided what it said was evidence that election workers were backdating late ballots to allow them to count. The judge dismissed that claim as hearsay and denied the campaign's request, though, and state officials have since come out to debunk the claim.
In a statement, a Detroit official confirmed that no ballots were incorrectly backdated. Rather, there was a clerical issue with ballot dates that had to be remedied, a process he said Republican challengers were involved in and did not object to at the time.
The error occurred when some ballots were received at Detroit offices: an employee stamped the receipt date on the ballot envelopes, but never saved that date in the e-file. At a later date, that earlier receipt date, the correct date, was entered into the e-file.
According to the statement, this was done to ensure that "no voters were disenfranchised by the clerical error." Biden led Trump there by nearly 149,000 votes as of Nov. 12.
False claim: "Software glitch" caused ballots to switch from Trump to Biden in Michigan
On Thursday, Trump tweeted that a software glitch in a widely used voting software system caused votes cast for Trump to be switched to votes for Joe Biden. The Trump campaign has presented the allegation as one basis for its legal challenges in Michigan, where Biden has a 3% lead. On Tuesday, the claim was included in a new lawsuit from the Trump campaign in Michigan seeking to halt the certification of results in the state, arguing any votes tabulated on Dominion equipment should not be counted.
But state officials from both parties say the claim is “categorically false.”
"The equipment and software did not malfunction and all ballots were properly tabulated," the Michigan Department of State said in a statement on Monday. "The software did not cause a misallocation of votes; it was a result of user human error. Even when human error occurs, it is caught during county canvasses."
Tina Barton, the city clerk of Rochester Hills and a Republican, said she was "disturbed" by the "categorically false" allegation that 2,000 votes in her jurisdiction were switched.
"This was an isolated mistake that was quickly rectified once realized," Barton said in the video statement. "I stand by our reported results."
In response to the president's tweet, Dominion, the voting system at issue, issued a statement categorically denying any claims about vote switching or alleged software issues, and took issue with those "exploiting incomplete and inaccurate scraps of information to sow doubt about the 2020 election results."
"Our systems continue to reliably and accurately count ballots, and state and local election authorities have publicly confirmed the integrity of the process," the statement said.
Previously, Dominion said they had received "no credible reports or evidence of any software issues."
Misleading claim: Observers were not granted access to see the vote counting process.
One of the most frequent claims made by the campaign is that it certified poll observers were not granted "meaningful access" to observe the vote counting process, which they have a legal right to do. Trump has complained that his campaign’s representatives were improperly shut out from canvassing facilities.
"Nobody wants to report that Pennsylvania and Michigan didn't allow our Poll Watchers and/or Vote Observers to Watch or Observe," Trump tweeted on Wednesday. "This is responsible for hundreds of thousands of votes that should not be allowed to count."
Numerous jurisdictions had both Republican and Democrat observers watching the vote count, and in some cases they were asked to stand farther away than customary to ensure social distancing during the COVID-19 pandemic. But there is no evidence that Republican challengers were entirely shut out during the counting process in any state.
The campaign's singular court victory since the election came when a Pennsylvania judge allowed observers to get closer to the counting process there. But that does not mean that there was fraud in the counting process -- the campaign has yet to provide any evidence of that -- and judges have rejected campaign efforts to cast doubt on ballots counted while challengers were further away.