Michael Cohen, who once said he would take a bullet for Donald Trump, was poised on Monday to serve as a star prosecution witness in the former US president’s criminal trial on charges of covering up hush money paid to a porn star.

Mr Cohen was expected to take the stand on day 16 of the trial in New York state court in Manhattan. His testimony marks the culmination of a 15-year arc from a lawyer and fixer for the businessman-turned-politician to an outspoken antagonist.

“I’m the guy who would take a bullet for the president,” Mr Cohen told Vanity Fair in 2017.

Two years later, facing a US congressional committee, Mr Cohen testified: “I am ashamed because I know what Mr Trump is. He is a racist. He is a con man. He is a cheat.”

Stormy Daniels payment

The case against Mr Trump stems from Mr Cohen’s $130,000 (€121,000) payment to porn star Stormy Daniels before the 2016 election for her silence about a sexual encounter she alleges to have had with Mr Trump a decade earlier.

Mr Cohen, a top executive at Mr Trump’s real estate company before becoming his lawyer, says Mr Trump directed the payment.

Now 57, Mr Cohen spent more than a year in prison for crimes including a violation of federal election campaign finance laws with the payment to Ms Daniels. In 2020, he published a book about his experience working with Mr Trump called, “Disloyal: A Memoir”.

Mr Trump, the Republican presidential candidate in the November 5th election, has pleaded not guilty to 34 counts of falsification of business records to conceal the payment. He has also denied the encounter with Ms Daniels, whose given name is Stephanie Clifford, and called Mr Cohen a “serial liar”.

Mr Cohen turned on Mr Trump midway through his presidency, as federal investigators probed his role in the payment to Ms Daniels and other matters.

After Mr Trump’s own 2023 indictment, Mr Cohen said his goal in cooperating with authorities was to “speak truth to power”.

“If speaking truth to power makes me Donald’s arch-nemesis, so be it,” Mr Cohen told Reuters in a 2023 interview.

This will not be Mr Cohen’s first time testifying in court against Mr Trump. In a civil fraud case over the former president’s valuations of his real estate assets, Mr Cohen said on the stand in October he had manipulated the values of Mr Trump’s real estate properties to match “whatever number Mr. Trump told us”.

A judge in February ordered Mr Trump to pay $454 million (€420 million) in penalties and interest after finding that he misled lenders and insurers about the Trump Organisation’s property values. Mr Trump is appealing.

A prison sentence

Mr Cohen was hired as the Trump Organisation’s executive vice president and special counsel in 2007. Before that, the Long Island native and son of a Holocaust survivor worked as a malpractice lawyer and owned a fleet of yellow taxis.

He was hired after he had orchestrated the ouster of the board of directors of a condominium where he owned an apartment, which was trying to remove Mr Trump’s name from the building’s exterior.

Mr Cohen later advised Mr Trump’s 2016 presidential campaign and, as his personal lawyer, remained close to Mr Trump once he became president, though he did not have an official White House job.

In 2018, after the hush money payment to Ms Daniels came to light, Mr Cohen initially said he had paid with his own money and that neither the Trump campaign nor the Trump Organisation reimbursed him.

He later pleaded guilty to a federal campaign finance law violation for paying Ms Daniels and then testified in Congress that Mr Trump told him to make the payment. He said he was reimbursed in instalments and displayed a copy of a $35,000 (€32,000) check from Mr Trump’s personal bank account.

Mr Cohen was sentenced to three years in prison for the payment and other crimes, including cheating on his personal taxes and lying under oath to Congress about when the Trump Organisation stopped working on a proposed building project in Russia. Mr Cohen served more than a year before being released.

‘Part of the playbook’

Relying on Mr Cohen’s testimony presents risks for Manhattan district attorney Alvin Bragg, given the disbarred lawyer’s history of false statements.

Mr Cohen’s testimony at the civil fraud trial could provide fertile ground for Mr Trump’s defence lawyers during cross-examination at the criminal trial. At the civil trial, he said he lied to the federal judge who took his guilty plea in 2018 by admitting to tax fraud – a crime he now says he did not commit.

Mr Cohen, married with two children, has said he has taken responsibility for his wrongdoing. He has said much of his criminal conduct – including the lie to Congress and the Daniels payment – arose out of his blind loyalty to Mr Trump.

He told Reuters in the 2023 interview he expected Mr Trump and his allies to attack him.

“It’s all part of the playbook,” Mr Cohen said.