Trump judge urges lawyers to rein in Michael Cohen

The judge overseeing Donald Trump's criminal trial has urged prosecutors to tell the former US president's estranged former lawyer and fixer Michael Cohen to stop making public statements about the case before his expected testimony next week.

Todd Blanche, Trump's defence lawyer in the case stemming from hush money paid to a porn star, said Cohen, the star prosecution witness, had spoken on social media on Wednesday while wearing a T-shirt showing Trump, the Republican presidential candidate, behind bars.

Justice Juan Merchan suggested prosecutors tell Cohen that the request to refrain from public statements "comes from the bench." He spoke at the close of the 15th day of the first criminal trial of a sitting or former US president.

Trump Hush Money Who's Who
Donald Trump's lawyers have been told to rein in 'fixer' Michael Cohen from speaking publicly. (AP PHOTO)

Prosecutors with Manhattan District Attorney Alvin Bragg's office said they would pass along the message. Cohen's lawyer did not immediately respond to a request for comment on the judge's comments or the timing of his expected testimony.

Cohen's highly anticipated testimony against his former boss - a man he once said he would take a bullet for - is crucial to the prosecution case.

Trump is accused of fudging his family real estate company's records to cover up Cohen's $US130,000 ($A196,821) payment to porn star Stormy Daniels for her silence before the 2016 election about a sexual encounter she alleges she and Trump had in 2006.

Trump, 77, has pleaded not guilty to 34 counts of falsifying business records and denies having sex with Daniels, 45.

Before the trial adjourned ahead of the weekend, Assistant District Attorney Joshua Steinglass said prosecutors would call two witnesses on Monday and predicted they could rest their case by the end of next week.

Cohen said on a podcast on Thursday that he expected to testify next week.

Trump has called the case a politically motivated effort to interfere with his campaign to win back the White House  in the November 5 US election against his Democratic opponent, President Joe Biden.

Merchan has fined Trump $US10,000 ($A15,140) for running afoul of a gag order restricting his public statements about witnesses, jurors and others involved in the case, and warned the former president he may jail him for future violations.

Trump has argued the gag order impedes his constitutional right to free speech, and has complained that he cannot respond to public criticism from witnesses like Cohen and Daniels.

"He wants to put me in jail. And that could happen one day and I'd be very proud to go to jail for our Constitution," Trump told reporters after the trial ended for the day.

Prosecutors say the payments to Daniels and another woman who says she had an affair with Trump, Playboy model Karen McDougal, were part of a broader scheme to corrupt the 2016 election by buying the silence of people with potentially damaging information in violation of campaign finance laws.

Trump defeated Democrat Hillary Clinton in the race for president that year. Trump denies having had an affair with McDougal, who is not expected to testify.