After Davidson testified that he arranged the $US130,000 ($A198,000) payment with Trump's personal lawyer Michael Cohen, Bove asked about Davidson's alleged efforts to seek cash from Hulk Hogan in exchange for a sex tape involving the former pro wrestler.

He also asked Davidson about attempts to trade embarrassing information for cash from celebrities including actor Charlie Sheen and reality TV star Tila Tequila.

“You were pretty well-versed in getting right up to the line without committing extortion, right?” Bove asked.

Davidson denied ever committing extortion.

Trump's lawyers are likely to take a similar tack with other expected witnesses including Daniels, whose real name is Stephanie Clifford, and Cohen, who has served prison time for his role in the payment scheme.

Davidson confirmed Daniels signed a non-disclosure agreement with Trump to keep quiet about a 2006 sexual encounter, but said he would not describe the payment as hush money. "It was consideration in a civil settlement agreement," he said.

Davidson said the forceful denial he helped Daniels craft when the payment was revealed in 2018 did not amount to a lie because it referred to a "romantic sexual" relationship rather than a one-off sexual encounter.

“You have to go through it word by word, and I think if you did so, it would technically be true with an extremely fine reading,” he said.

Daniels later disavowed the statement and said the signature on it was not hers.

Earlier in the day, Justice Juan Merchan signaled he might fine Trump over allegations he again violated a gag order that prohibits him from making public comments about jurors, witnesses, and families of the judge and prosecutors if those statements are meant to interfere with the case.

Merchan challenged a defence assertion that Trump did not violate the gag order when he said the Manhattan jury in the first criminal trial of a former US president was picked from a heavily Democratic area.

“I’m making an argument that he didn’t,” Trump lawyer Todd Blanche told the judge.

“Well I’m not agreeing with that argument,” Merchan responded without saying whether or when he would impose a fine.

Prosecutors are asking Merchan to fine Trump $US4000 ($A6000) for violating the gag order four times last week. In one instance, the Republican Trump said in a TV interview that "that jury was picked so fast - 95 per cent Democrats. The area's mostly all Democrat."

"By speaking about the jury at all, he places this proceeding in jeopardy," prosecutor Christopher Conroy said.

Conroy said Trump also violated the gag order by calling Cohen a liar and former National Enquirer publisher David Pecker a "nice guy." Pecker testified last week and Cohen is expected to be a crucial witness in the case.

Blanche said there was "no threat" in what Trump said about Pecker and said Cohen, in his social media comments, has been "inviting, and almost daring" Trump to respond to his comments about the trial.

Trump claims prosecutors are working with Democratic President Joe Biden to undercut his bid to win back the White House and says Merchan faces a conflict of interest because his daughter has done work for Democratic politicians.

Trump faces three other criminal prosecutions, though it is not clear whether any of them will go to trial before the November 5 presidential election. Two accuse him of trying to overturn his 2020 election loss to Biden, while another accuses him of mishandling classified documents after leaving office. He has pleaded not guilty in all three cases.