One of Trump’s Oldest Tactics in Business and Politics: I’m Rubber. You’re Glue.

Days before the Iowa caucuses, former President Donald J. Trump is appearing twice in court this week — on Tuesday in Washington and Thursday in New York.

He was not required to attend either hearing. But advisers say he believes the court appearances dramatize what is fast becoming a central theme of his campaign: that President Biden — who is describing the likely Republican nominee as a peril to the country — is the true threat to American democracy.

Mr. Trump’s claim is the most outlandish and baseless version of a tactic he has used throughout his life in business and politics. Whenever he is accused of something — no matter what that something is — he responds by accusing his opponent of that exact thing. The idea is less to argue that Mr. Trump is clean than to suggest that everyone else is dirty.

It is an impulse more than a strategy. But in Mr. Trump’s campaigns, that impulse has sometimes aligned with his political interests. By this way of thinking, the more cynical voters become, the more likely they are to throw their hands in the air, declare, “They’re all the same” and start comparing the two candidates on issues the campaign sees as favorable to Mr. Trump, like the economy and immigration.

His flattening moral relativism has undergirded his approach to nearly every facet of American public life, including democracy.

In 2017, when the Fox News host Bill O’Reilly described President Vladimir Putin of Russia as a “killer,” Mr. Trump responded that there were “a lot of killers,” adding, “Well, you think our country is so innocent?”

And in the 2016 campaign, Mr. Trump applied the “I’m rubber, you’re glue” approach to a wide range of vulnerabilities.

When Mr. Trump was described by voters as racist in polls after, among other things, he described undocumented immigrants from Mexico as “rapists,” he claimed that his rival, Hillary Clinton, was the true “bigot.”

When Mrs. Clinton suggested he was temperamentally unfit to be entrusted with the nation’s nuclear codes, Mr. Trump declared her “trigger happy” and “very unstable.”

When Mrs. Clinton called Mr. Trump a “puppet” of Mr. Putin during one of their general election debates, Mr. Trump interrupted: “No puppet. You’re the puppet.”

A spokesman for Mr. Trump did not respond to requests for comment.

For years, Mr. Trump championed and breathed life into the previously fringe “birther” movement that falsely claimed Barack Obama had been born in Kenya and was therefore an illegitimate president. When he finally renounced the conspiracy theory out of political expediency shortly before Election Day in 2016, he falsely claimed that it was Mrs. Clinton who had started attacking the first Black president with that assertion.

Senator Ted Cruz of Texas — “Lyin’ Ted,” Mr. Trump had dubbed him — was a victim of this Trumpian tactic in the 2016 Republican presidential primaries at a time when Mr. Trump was being called out for almost constant falsehoods. Mr. Cruz once summarized the injustice in a fit of indignation, saying of Mr. Trump: “He lies — practically every word that comes out of his mouth. And in a pattern that I think is straight out of a psychology textbook, his response is to accuse everybody else of lying.”

Now, Mr. Trump is repurposing his favored tool to neutralize what many see as his worst offense in public life and greatest political vulnerability in the 2024 campaign: his efforts, after he lost the 2020 election, to disrupt the peaceful transfer of power and remain in office.

And his campaign apparatus has kicked into gear along with him, as he baselessly claims Mr. Biden is stage-managing the investigations and legal action against him. Mr. Trump’s advisers have coined a slogan: “Biden Against Democracy.” The acronym: BAD.

Steve Bannon, Mr. Trump’s former chief strategist, said he thought his onetime client was on to something. Mr. Trump is now fighting Mr. Biden over an issue that many Republican consultants and elected officials had hoped he would avoid. They had good reason, given that candidates promoting election denial and conspiracy theories about the Jan. 6, 2021, attack on the Capitol cost their party winnable races in the 2022 midterm elections.

Mr. Bannon sees it differently.

“If you can fight Biden almost to a draw on this, which I think you can, it’s over,” Mr. Bannon said in an interview, referring to the imperiling of American democracy. “He’s got nothing else he can pitch. This is his main thing.”

Mr. Bannon added, “If Biden wants to fight there, about democracy and all this kind of ephemeral stuff, Trump will go there in a second.”

It was Mr. Bannon who pushed for Mr. Trump to “go on offense” after a tape leaked of him boasting to the TV host Billy Bush about grabbing women’s genitals. Mr. Bannon helped arrange for three women who had accused former President Bill Clinton of sexual harassment or assault to join Mr. Trump at a news conference shortly before a debate with Mrs. Clinton. It created a disorienting effect at a moment of acute vulnerability for Mr. Trump.

“You’ve got to remember something,” Mr. Bannon said of the Trump campaign’s “Biden Against Democracy” gambit. “This is the whole reason he’s actually running: to say he believes that, burned into his soul, is the 2020 election was stolen, and that Jan. 6 was a setup by the F.B.I.”

It’s unclear whether Mr. Trump actually believes that Jan. 6 was orchestrated by the “deep state.” His explanations of that day have shifted opportunistically, and he was a relative latecomer to the baseless far-right conspiracy theory that the Capitol riot was an inside job by the F.B.I.

Mr. Trump has also sought to muddy the waters on voter concerns about corruption, by trying, along with his allies, to neutralize his liabilities on that front by attacking Mr. Biden’s son, Hunter, for foreign moneymaking while his father was vice president.

But some of Mr. Trump’s advisers think there is less to gain from the Hunter Biden angle than from the “Biden Against Democracy” theme. They recognize that Hunter Biden is not the president and doubt the issue will move voters significantly without the emergence of a connection to the president strong enough to convince Senate Republicans who remain skeptical that there is a basis for impeachment.

Mr. Trump has also privately expressed concern about overplaying personal attacks on the president’s son to such an extent that they backfire and make Mr. Biden look like a caring father, according to a person who has heard Mr. Trump make these remarks.

In a 2020 general election debate, Mr. Trump made such an error, when he mocked Hunter Biden’s past drug use, prompting a humanizing response from Mr. Biden: “My son, like a lot of people, like a lot of people you know at home, had a drug problem. He’s overtaken it. He’s fixed it. He’s worked on it. And I’m proud of him.”

Mr. Trump and his advisers are hoping to do more than paper over his liabilities related to his election lies and the violent attack on the Capitol, which Democrats are confident remain deeply troubling to a majority of voters. They hope they can persuade voters that Mr. Biden is actually the problem.

Voter attitudes related to Mr. Biden have shifted as Mr. Trump has tried to suggest that efforts to hold Mr. Trump accountable for his actions are a threat to democracy. In an October 2022 New York Times/Siena College poll, among voters who said democracy was under threat, 45 percent saw Mr. Trump as a major threat to democracy, compared with 38 percent who said the same about Mr. Biden. The gap was even wider among independent voters, who were 14 percentage points more likely to see Mr. Trump as such a threat.

But Mr. Trump’s rhetoric seems to have already altered public opinion, even before the campaign deployed his new slogan. In another more recent survey, 57 percent of Americans said Mr. Trump’s re-election would pose a threat to democracy, and 53 percent said the same of Mr. Biden, according to an August 2023 poll by the Public Religion Research Institute. Among independent voters, nearly identical shares thought either candidate would be a threat to democracy.

The repetition that Mr. Trump has used consistently in his public speeches is a core part of his approach.

“If people think he’s inconsistent on message, he ain’t inconsistent on this message,” Mr. Bannon said of Mr. Trump’s effort to brand Mr. Biden as the real threat to democracy. “Go back and just look at how he pounds it. Wash, rinse, repeat. Wash, rinse, repeat. It’s very powerful.”

David Axelrod, a former top adviser to Mr. Obama, said polling indicated Mr. Trump had “made headway with his base in this project.” But a general election, he said, is a “harder” race to convince people that his lies about Jan. 6, 2021, are true.

It is “one of the reasons he’s so desperate to push the Jan. 6 trial past the election,” Mr. Axelrod said of the federal indictment charging Mr. Trump with conspiracy to defraud the United States.

“A parade of witnesses, including his own top aides, White House lawyers and advisers, testifying, followed by a guilty verdict, would damage him outside the base,” Mr. Axelrod said.

Ruth Igielnik contributed reporting.