At rally after rally, he urges his supporters to deliver a victory "too big to rig," telling them the only way he can lose is if Democrats cheat. He has refused to say, repeatedly, whether he will accept the results regardless of the outcome. And he's claimed cheating is already underway, citing debunked claims or outrageous theories with no basis in reality.

"The only thing that can stop us is the cheating. It's the only thing that can stop us," he said at an event in Arizona late Thursday night.

In 2020, Trump prematurely declared victory from the White House. He launched a legal and political effort to overturn his loss to Democrat Joe Biden that culminated in the storming of the Capitol by his supporters on Jan. 6, 2021.

Democrats fear he may do the same thing this year before the race is called. He wouldn't answer a question Friday in Dearborn, Michigan, about those Democratic concerns, instead pivoting to attacking Vice President Kamala Harris.

Trump has made election lies central to his 2024 campaign, issuing fevered warnings about fraud while promising to take retribution against people he sees as standing in his way.

This year, he is backed by a sophisticated "election integrity" operation built by his campaign and the Republican National Committee that has filed more than 130 lawsuits already and signed up more than 230,000 volunteers being trained to deploy as poll watchers and poll workers across the country on Election Day.

Here's a look at Trump's strategy to sow doubt in this year's election and the facts behind each claim.

Non-citizen voting

THE CLAIM: Trump has alleged, without evidence, that Democrats have allowed millions of migrants to enter the country illegally so that they can be registered to vote. In an interview with Newsmax in September, Trump alleged such efforts were already underway.

"They are working overtime trying to sign people, illegally, to vote in the election," he claimed. "They're working overtime to sign people and register people -- many of the same people that you just see come across the border. Which is probably their original thought, because why else would they want to destroy our country?"

THE FACTS: It takes years for newcomers to become citizens and only citizens can legally cast ballots in federal elections. Isolated cases of noncitizens being caught trying to vote -- like a University of Michigan student from China arrested for allegedly casting an illegal ballot -- do not reflect a larger conspiracy.

Research has shown noncitizens illegally registering and casting ballots is extremely rare and usually done by mistake.

Overseas ballots

THE CLAIM: Trump has pointed to Democratic efforts to secure the votes of Americans living abroad as another opportunity for fraud. He's alleged that they are "getting ready to CHEAT!" and "want to "dilute the TRUE vote of our beautiful military and their families."

THE FACTS: The former president has himself campaigned for the votes of Americans overseas, promising to end so-called "double taxation" for people who often pay taxes in the country where they reside as well as to the U.S. government.

Ominous warnings

THE CLAIM: Trump has begun to suggest that Harris might have access to some kind of secret inside information about the outcome of a race that has yet to be decided.

Since the vice president took a day off from the trail to sit for interviews with Telemundo and NBC, he has repeatedly suggested, "Maybe she knows something we don't know."

In Michigan last weekend, he suggested there is no way Harris would be campaigning with Beyonce -- one of the biggest stars in the world -- if the race were really as close as polls suggest.

"Number one, they cheat like hell. So maybe they know something that we don't, right?" he said. "They might know something that we don't, I don't know. Why the hell would she be celebrating when you're down? Maybe -- never thought of that -- maybe she knows something we don't. But we're not going to let it happen."

THE FACTS: There is no evidence to support a Democratic conspiracy. Indeed, Trump fanned fears of his own inside planning at a rally at New York's Madison Square Garden when he looked at House Speaker Mike Johnson and talked about a "little secret" they had.

Johnson, before becoming speaker, took the lead in drafting a widely panned brief seeking to overturn Trump's 2020 loss and echoed some of the wilder conspiracy theories to explain away his loss.

Asked about Trump's reference to a "little secret," Johnson issued a statement that included the following: "By definition, a secret is not to be shared -- and I don't intend to share this one." (He later told an audience that it related to "one of our tactics on get-out-the-vote," according to The Hill. Trump's campaign issued a statement noting he had "done countless tele-rallies" to help bolster Republican congressional candidates.)

Turning to Pennsylvania

THE CLAIM: Trump in recent days has turned his ire on Pennsylvania, a state that both campaigns view as critical, and where he's claimed cheating is already underway.

Earlier this week, he claimed York County, Pennsylvania, had "received THOUSANDS of potentially FRAUDULENT Voter Registration Forms and Mail-In Ballot Applications from a third party group." He has also pointed to Lancaster County, which he claimed had been "caught with 2600 Fake Ballots and Forms, all written by the same person. Really bad 'stuff.'"

During a campaign event in Allentown on Tuesday, the former president said: "They've already started cheating in Lancaster. They've cheated. We caught 'em with 2,600 votes. No, we caught them cold. 2,600 votes. Think of this, think of this. And every vote was written by the same person."

THE FACTS: In Lancaster, County District Attorney Heather Adams, an elected Republican, has said election workers raised concerns about two sets of voter registration applications because of what she described as numerous similarities. Officials are now examining a total of about 2,500 forms.

To be clear, Lancaster is looking into voter registration applications, not "votes." Lancaster officials said some forms contained false names, suspicious handwriting, questionable signatures, incorrect addresses or other problematic details, but did not say they were all written by the same person.

York County Chief Clerk Greg Monskie confirmed this week that his county was reviewing suspect forms. County Commissioner Julie Wheeler issued a statement saying voter registration forms and mail-in ballot applications were among a "large delivery containing thousands of election-related materials" that the county elections office received from a third-party organization.

Officials in the state say the discovery and investigation into the applications -- not votes -- is evidence the system is working as it should.

Threats of prosecution

THE CLAIM: Trump has threatened severe consequences for those engaged in what he deems "unscrupulous behavior."

In one social media post that falsely cites "the rampant Cheating and Skullduggery that has taken place by the Democrats in the 2020 Presidential Election," he has warned that, "WHEN I WIN, those people that CHEATED will be prosecuted to the fullest extent of the Law, which will include long term prison sentences."

The posts go on to threaten "Those involved in unscrupulous behavior," including election officials, lawyers, and donors, whom he says "will be sought out, caught, and prosecuted at levels, unfortunately, never seen before in our Country."

THE FACTS: Judges, election officials and even Trump's own attorney general, William Barr, have all affirmed that there was no widespread cheating in the 2020 election.

If he's elected again, Trump has vowed to go after rivals he has deemed "enemies from within," including saying he would appoint a special prosecutor to target Biden. That's more than a theoretical threat given that when he was president, Trump repeatedly pressed for investigations into perceived political adversaries.

While the Justice Department does have checks in place meant to ward off political influence, Trump could appoint leaders who would facilitate cases being opened at his behest.

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Associated Press writers Christine Fernando in Chicago, Adriana Gomez Licon in Dearborn, Michigan, and Eric Tucker in Washington contributed to this report.