A colorful former tabloid publisher took the witness stand Tuesday at Donald Trump's "hush money" trial and testified how he suppressed negative stories about the real estate tycoon, a practice known as "catch and kill."

Trump, 77, the first former US president to face criminal charges, is accused of falsifying business records to buy the silence of porn star Stormy Daniels over a 2006 sexual encounter that could have damaged his 2016 presidential bid.

Trump's former personal lawyer Michael Cohen allegedly arranged a $130,000 hush money payment to the adult film actress on the eve of the 2016 election between Trump and Hillary Clinton.

David Pecker, 72, former publisher of the National Enquirer, was the first witness called to testify by prosecutors at Trump's high-stakes trial, which comes less than seven months ahead of his expected White House rematch against President Joe Biden.

Pecker took the stand after a nearly 90-minute hearing during which Judge Juan Merchan was asked by prosecutors to hold Trump in contempt of court for violating a partial gag order preventing him from intimidating witnesses.

Merchan, who imposed the gag order on April 1, heard arguments from prosecutors and defense attorneys but did not issue an immediate ruling.

Pecker said he has known Trump since 1989 and described him as a friend -- "I would call him Donald."

He said National Enquirer readers "loved" Trump, who starred in the hit reality television series "The Apprentice" before going into politics in 2015.

"They followed him religiously," Pecker said, and a poll conducted by the tabloid found that "80 percent' of the readership would vote for Trump for president.

"I passed that information on to Mr Trump," he said.

 'Help the campaign' 

 Pecker said he agreed at an August 2015 meeting at Trump Tower with Trump, Cohen and Trump's personal assistant Hope Hicks to help his friend's nascent campaign for the 2016 Republican presidential nomination.

"They asked me what can I do and what my magazines can do to help the campaign," he said.

"I said what I would do is, I would run or publish positive stories about Mr Trump and I would publish negative stories about his opponents."

He said he would reach out to Cohen to warn him about potential negative stories about Trump.

"When I notified Michael Cohen of a story that was a negative story, he would try to vet it himself, see if the story was true or not," Pecker said. "And he would go to the individual publication to make sure the story wasn't published and get it killed."

Although Pecker was not personally involved in the payment to Daniels, prosecutors are seeking his testimony to demonstrate that the "catch and kill" practice was one commonly used by Trump and his "fixer" Cohen.

 Trump slams judge 

 Before Pecker took the stand, prosecutors accused Trump of brazenly violating the gag order imposed by the judge.

Trump's "willful" and "intentional" attacks on witnesses "clearly violate" the gag order, prosecutor Chris Conroy said, urging the judge to fine him $1,000 per violation.

"We are not yet seeking an incarceratory penalty," Conroy said, but the court should "remind him that an incarceration is an option should it be necessary."

Jailing Trump could potentially set up a conflict with the Secret Service, which is charged with protecting former and current presidents.

Trump lashed out at the judge following the contempt hearing, saying he "has taken away my constitutional right to free speech."

"Everybody is allowed to talk and lie about me, but I am not allowed to defend myself," Trump complained on his Truth Social platform. "This is a kangaroo court, and the judge should recuse himself!"

Daniels and Cohen are both expected to appear as prosecution witnesses at the trial.

Trump has repeatedly attacked them on Truth Social, calling them, for example, "sleaze bags who have, with their lies and misrepresentations, cost our country dearly."

Trump has repeatedly denounced the case as a "witch hunt" designed to keep him off the campaign trail ahead of the November election.