Donald J. Trump, the onetime president, and Stormy Daniels, the longtime porn star, despise one another. But when Ms. Daniels returned to the witness stand at Mr. Trump’s criminal trial on Thursday, his lawyers made them sound a lot alike.
He wrote more than a dozen self-aggrandizing books; she wrote a tell-all memoir. He mocked her appearance on social media; she fired back with a scatological insult. He peddled a $59.99 Bible; she hawked a $40 “Stormy, saint of indictments” candle, that carried her image draped in a Christ-like robe.
During Thursday’s grueling cross-examination, Mr. Trump’s lawyers sought to discredit Ms. Daniels as a money-grubbing extortionist who used a passing proximity to Mr. Trump to attain fame and riches. But the more the defense assailed her self-promoting merchandise and online screeds, the more Ms. Daniels resembled the man she was testifying against: a master of marketing, a savant of social-media scorn.
“Not unlike Mr. Trump,” she said on the stand, though unlike him, she did it without the power and platform of the presidency.
Ms. Daniels’s appearance plunged the proceeding into turmoil as the defense pleaded with the judge to declare a mistrial in the first criminal trial of an American president. Ms. Daniels’s graphic account of a sexual encounter with Mr. Trump, they argued, had inflicted irreparable damage on the defense.
But the judge, Juan M. Merchan, rejected the request and rebuked defense lawyers, noting that their decision to deny that the tryst had even occurred opened the door for much of her explicit testimony. Ms. Daniels offered jurors a first-person account of the encounter with Mr. Trump, helping prosecutors bolster belief in an incident that underpins the case.
Her appearance also laid the groundwork for the prosecution’s star witness, Michael D. Cohen, who is expected to take the stand Monday, according to people with knowledge of the matter. Mr. Cohen, Mr. Trump’s former fixer, bought Ms. Daniels’s silence in the final stretch of the 2016 presidential campaign, the payoff that led to the charges against Mr. Trump, who is accused of falsifying records to cover up the scandal.
Over nearly eight hours of searing testimony across two days, Ms. Daniels recounted her story of a sexual encounter with Mr. Trump in 2006. She described accepting the $130,000 hush-money payment during his first presidential campaign. And, facing combative questions from his lawyers about subtle shifts in her story, she swung between defiance and vulnerability.
After a shaky performance on the stand earlier in the week, Ms. Daniels on Thursday conceded almost nothing. She had been frazzled. Now she was nimble as she volleyed with her questioner.
Susan Necheles, a lawyer for Mr. Trump, grilled Ms. Daniels about her account of a one-night stand at a celebrity golf tournament in Nevada: “You made all this up, right?”
Ms. Daniels responded with a forceful “no.”
When Ms. Necheles suggested that the porn star had experience with “phony stories about sex,” Ms. Daniels responded that the sex in her films is “very much real, just like what happened to me in that room.” And when Ms. Necheles implied that her experience producing films showed that she knew how to spin fiction, Ms. Daniels replied, “I would have written it to be a lot better.”
Ms. Daniels, wearing a dark green dress and a long black cardigan, showed sensitivity at odds with the defense’s gold-digging portrayal. When a prosecutor asked her a final question — whether her experience with Mr. Trump had been positive or negative — she choked up.
“Negative,” Daniels said, barely getting the word out, seemingly on the verge of tears.
Mr. Trump’s lawyers conveyed incredulity, noting that Ms. Daniels had denied the fling at various points. They unearthed inconsistencies, most notably Ms. Daniels’s insistence that she had wanted her story out in the world and had little interest in money. Ms. Necheles, spotlighting Ms. Daniels’s effort to sell the story to the media as well as to Mr. Trump, suggested that in fact Ms. Daniels had shaken him down.
“That’s what you were asking in 2016, was for money, to be able to tell your story?” Ms. Necheles asked pointedly, adding, “That was your choice, right?”
Ms. Daniels resisted, saying she “accepted an offer” from Mr. Cohen in the waning days of the 2016 campaign because she was “running out of time.”
But Ms. Necheles noted that she could have told her story for free. She pointed to evidence that Ms. Daniels had flirted with doing so but had abandoned discussions with a reporter from Slate magazine.
“You could have gone out any day of the week” and given a news conference, Ms. Necheles said, “but you chose not to, right?”
The defense chipped at Ms. Daniels’s credibility after she spent much of her earlier testimony describing an encounter with Mr. Trump in a sprawling Lake Tahoe, Nev., hotel suite in 2006.
In lurid detail — so much so that the judge scolded her Tuesday — Ms. Daniels painted the scene. She told jurors about Mr. Trump’s underwear, the sexual position they assumed and his flirtatious chitchat likening her to his daughter: “She is smart and blond and beautiful, and people underestimate her as well.”
But the testimony, while striking, was something of a sideshow to the trial’s main event. There is nothing illegal about a married man having sex with a porn star, nor is it inherently criminal to pay a person for silence.
And Ms. Daniels knew nothing about the records that, according to prosecutors, Mr. Trump falsified to conceal his repayment of Mr. Cohen for the $130,000 hush-money deal.
Citing her distance from the records, Mr. Trump’s lawyers sought a mistrial for the second time this week, arguing Ms. Daniels’s testimony was irrelevant and prejudicial. “It almost defies belief that we’re here about a records case,” his lead lawyer, Todd Blanche, argued. The defense also asked to alter a gag order to let Mr. Trump dispute Ms. Daniels’s testimony.
Justice Merchan denied both requests, and chided Mr. Trump’s lawyers for missteps during the prosecution’s examination of Ms. Daniels, saying they did not object often enough. He also suggested that the former president’s own insistence on denying any sexual encounter with Ms. Daniels had allowed the prosecution to introduce evidence that it did in fact occur.
“That, in my mind, allows the people to do what they can to rehabilitate her and to corroborate her story,” he said.
After Ms. Daniels left the stand, prosecutors called witnesses more directly related to the records. They questioned Rebecca Manochio, a junior bookkeeper at the Trump Organization, who described mailing Mr. Cohen’s checks, his reimbursements for payments to Ms. Daniels, to Washington for Mr. Trump to sign during his presidency.
They also called Madeleine Westerhout, one of Mr. Trump’s most trusted aides in the early White House years. She sat at a desk right outside the Oval Office and coordinated many of his communications, including a crucial meeting with Mr. Cohen just weeks into his term. Mr. Cohen is expected to testify that they discussed the plan to falsify the records — recording the payments as ordinary “legal expenses” — and Ms. Westerhout confirmed the meeting was scheduled.
She also confirmed that Mr. Trump paid close attention to checks he signed in the White House.
That testimony, somewhat anticlimactic after two days of a porn star’s stories of sex and scandal, could nonetheless corroborate components of Mr. Cohen’s story. And ultimately, the verdict could hang on his words — as well as the question of whether the jurors blame the prosecution or Mr. Trump for subjecting them to hours of squirm-inducing testimony.
For most of Thursday, Ms. Daniels appeared calm and controlled as she quibbled over the most trivial of facts. She never broke down, even when Ms. Necheles, with a hostile tone, accused her of capitalizing on her brush with Mr. Trump’s fame.
When Ms. Necheles displayed on the courtroom screens an advertisement for her strip club tour entitled “Make America Horny Again,” Ms. Daniels said that she had hated that tagline.
When the defense played a recording of Ms. Daniels’s lawyer telling Mr. Cohen that she was desperate for money, Ms. Daniels denied saying anything of that nature.
And when Ms. Necheles accused Ms. Daniels of extortion, remarking “You were threatening to try to hurt” Trump “if he didn’t give you money,” the witness returned to one of her common refrains of the week: “False.”
Ms. Daniels said that after paying expenses, including legal fees, she netted less than $100,000 from the hush money. And despite her vast array of online merchandise — including T-shirts and comic books, some aimed at the anti-Trump resistance — she said she had yet to turn a profit.
“It covers my travel and my expenses and my security,” she explained as Mr. Trump leaned forward and stared at the screen that displayed the exhibits of her entrepreneurial efforts.
Ms. Daniels noted that she is hardly unique. Mr. Trump is himself a branding virtuoso and an evangelist for unbridled capitalism. He once wrote a book called “How to Get Rich.”
And confronted with her schoolyard insults aimed at the former president, she again cast him as the instigator.
He had belittled her appearance, calling her “horse face.” She mocked him as an “orange turd.”
“I’m not a human toilet,” she said Thursday, “so if they want to make fun of me, I can make fun of them.”
Jonathan Swan, Matthew Haag, Kate Christobek and Wesley Parnell contributed reporting.
