Donald J. Trump first ran for president as a Republican nearly a decade ago.
Now, as he runs again in a political climate that he helped create, his Manhattan criminal trial is partly a referendum on his tactics during that first campaign.
The trial’s very premise is that prosecutors believe Mr. Trump orchestrated an election interference scheme. Faced with damaging stories that could have doomed his campaign — sex scandals involving a porn star and a Playboy model, for example — he concealed them, the prosecutors say.
But in a development that will bolster their case, prosecutors on Monday secured permission from the judge to admit evidence connected to Mr. Trump’s overall political strategy in 2016. Much of it bears the former president’s imprint: aggressive tweets, false denials, coordination with a tabloid publisher and more.
The judge’s ruling showed how the weapons that worked so well for Mr. Trump then are being turned against him in the courtroom now.
The techniques prosecutors highlighted Monday were not invented by Mr. Trump for use in his campaign; they are behaviors he exhibited throughout his life as a businessman and a reality-television star. But in modern American political history, such raw tactics had rarely been seen at such a high level.
One example is Mr. Trump’s relationship with The National Enquirer tabloid and its publisher, David Pecker, who is expected to appear as a witness.
The Manhattan district attorney’s office, which brought the case, obtained permission from the judge on Monday to introduce evidence related to a 2015 meeting among Mr. Trump, Mr. Pecker and Mr. Trump’s former fixer, Michael D. Cohen. A prosecutor, Joshua Steinglass, said on Monday that the three men had “conspired to influence the 2016 election.”
That meeting laid the groundwork for hush-money deals with a porn star, Stormy Daniels, and a Playboy model, Karen McDougal. But another result of that meeting, Mr. Steinglass said, were explosive headlines about Mr. Trump’s opponents in the Republican primary, including those claiming that Ben Carson had committed “medical malpractice” and that Senator Ted Cruz had a “family connection to J.F.K.’s assassin.”
A lawyer for Mr. Trump, Todd Blanche, protested the admission of evidence related to that meeting, saying that newspaper publishers met with candidates “all the time,” and that there was nothing improper about it, let alone illegal.
That admission worked against him. The judge, Juan M. Merchan, said that he was glad that Mr. Blanche believed that there was nothing wrong with the meeting — because it meant that he should not mind that the evidence would be introduced.
“There is no reason not to allow it in,” Justice Merchan said.
Mr. Steinglass won again when he persuaded Justice Merchan to admit evidence of the Trump campaign in crisis after the publication in 2016 of the infamous “Access Hollywood” tape, in which Mr. Trump boasted about grabbing women by their genitals.
“The video sent the campaign into a tailspin,” Mr. Steinglass said.
He offered up an email sent by a Washington Post reporter to Hope Hicks, Mr. Trump’s campaign spokeswoman. Mr. Steinglass said that Ms. Hicks had forwarded the exchange to Stephen K. Bannon, Kellyanne Conway and other members of the campaign team, “suggesting that their response should be to deny, deny, deny.” Eventually, he said, Mr. Bannon sent it to Mr. Cohen.
Mr. Blanche again protested, but was again rebuffed. The judge said he would allow jurors to see the email, saying that the ensuing thread was relevant.
The exchanges that prosecutors and defense lawyers debated on Monday underscored Mr. Trump’s penchant for delegating dirty work to others, giving himself some distance in the process.
The hush-money deals worked that way: Mr. Cohen paid off Ms. Daniels, while The National Enquirer bought Ms. McDougal’s silence. (Mr. Trump is charged with 34 counts of falsifying business records related to his reimbursement of Mr. Cohen.)
That habit is still on display this year, and can be helpful given that Justice Merchan has barred Mr. Trump from attacking witnesses, prosecutors and the judge’s own family.
On Tuesday, Mr. Trump posted on social media a video of Laura Loomer, a political ally, in the park outside the courthouse. Ms. Loomer, speaking into a bullhorn, insinuated that the judge’s family was politically compromised.
Had Mr. Trump said that himself, he would have risked violating the judge’s gag order.
