NEW YORK — Donald Trump’s fixer-turned-foe, Michael Cohen, directly implicated the former president in a hush money scheme Monday, telling jurors that his celebrity client approved hefty payouts to stifle stories about sex that he feared could be harmful to his 2016 White House campaign.

“You handle it,” Cohen quoted Trump as telling him after learning that a doorman had come forward with a claim that Trump had fathered a child out-of-wedlock. The Trump Tower doorman was paid $30,000 to keep the story “off the market” even though the claim was ultimately deemed unfounded.

A similar episode occurred after Cohen alerted Trump that a Playboy model was alleging that she and Trump had an extramarital affair. Again, the order was clear: “Make sure it doesn’t get released,” Cohen said Trump told him. The woman, Karen McDougal, was paid $150,000 in a hush money arrangement that was made after Trump was given a “complete and total update on everything that transpired.”

“What I was doing was at the direction of and benefit of Mr. Trump,” Cohen testified.

Cohen, Trump’s former lawyer and personal fixer, is by far the Manhattan district attorney’s most important witness in the case, and his much-awaited appearance on the stand signaled that the first criminal trial of a former American president is entering its final stretch.

The testimony of a witness with such intimate knowledge of Trump’s activities could heighten the legal exposure of the presumptive Republican presidential nominee if jurors deem him sufficiently credible. But prosecutors’ reliance on a witness with such a checkered past — Cohen pleaded guilty to federal charges related to the payments — also carries sizable risks with a jury. In addition, it could be a boon to Trump politically as he raises money off his legal woes and paints the case as the product of a tainted criminal justice system.

Though jurors have heard from others about the tabloid industry practice of “catch-and-kill,” in which rights to a story are purchased so that it can then be quashed, Cohen’s testimony is crucial to prosecutors because of his proximity to Trump and because he says he was in direct communication with the then-candidate about embarrassing stories he was scrambling to prevent from surfacing.

Besides payments to the doorman and to McDougal, another sum went to porn actor Stormy Daniels, who told jurors last week that the $130,000 she received was meant to prevent her from going public about a sexual encounter she says she had with Trump in a hotel suite a decade earlier.

Cohen also matters because the reimbursements he received from that payment form the basis of the charges against Trump — 34 felony counts of falsifying business records. Prosecutors say the reimbursements were logged, falsely, as legal expenses to conceal the payments’ true purpose.

Cohen gave jurors an insider account of his negotiations with David Pecker, the then-publisher of the National Enquirer, and the newspaper’s top editor about suppressing stories harmful to Trump, an effort that took on added urgency following the October 2016 disclosure of an “Access Hollywood” recording in which Trump was heard boasting about grabbing women sexually.

The Daniels payment was finalized several weeks after that revelation, but much of Monday’s testimony centered on the deal earlier that fall with McDougal.

Pecker earlier testified that he had pledged to be the “eyes and ears” of the Trump campaign and was such a loyalist that he told Cohen that his publication maintained a “file drawer or a locked drawer as he described it, where files related to Mr. Trump were located,” according to testimony Monday.

Cohen testified that he went to Trump immediately after the National Enquirer alerted him to a story about the alleged McDougal affair. “Make sure it doesn’t get released,” he says Trump told him.

Trump checked in with Pecker about the matter, asking him how “things were going” with it, Cohen said. Pecker responded: “’We have this under control, and we’ll take care of this,’” Cohen testified.

Cohen also said he was with Trump as Trump spoke to Pecker on a speakerphone in his Trump Tower office.

“David stated it would cost $150,000 to control the story,” Cohen said. He quoted Trump as saying: “No problem, I’ll take care of it,” meaning that the payments be reimbursed.

To lay the foundation that the deals were done with Trump’s endorsement, prosecutors elicited testimony from Cohen — who spent a decade as a Trump Organization senior executive — designed to show Trump as a hands-on manager on whose behalf Cohen said he sometimes lied and bullied others, including reporters.

“When he would task you with something, he would then say, ‘Keep me informed. Let me know what’s going on,’” Cohen testified. He said that was especially true “if there was a matter that was troubling to him.”

“If he learned of it in another manner, that wouldn’t go over well for you,” Cohen testified.

Defense lawyers have teed up a bruising cross-examination of Cohen, telling jurors during opening statements that he’s an “admitted liar” with an “obsession to get President Trump.”

Prosecutors are expected to try to blunt those attacks by eliciting detailed testimony from Cohen about his past crimes. They have also called other witnesses whose accounts, they hope, will buttress Cohen’s testimony. Those witnesses included a lawyer who negotiated the hush money payments on behalf of Daniels and McDougal, as well as Pecker and Daniels.

Trump sat silently with his eyes closed as Cohen’s testimony covered the payoff to the doorman and other aspects of the hush money machinations. He did not appear to make eye contact with Cohen as the lawyer took the stand.