Donald Trump created a "false expectation" of his imminent arrest, the New York prosecutor investigating the ex-president over hush money said Thursday, as tensions build over a possible indictment.

The comments come amid uncertainty over when a grand jury hearing the case will take a vote on charging Trump, a historic move that would inflame the 2024 election campaign in which the 76-year-old Republican is running to regain office.

Manhattan District Attorney Alvin Bragg's office made the remarks in a letter sent to three Republican lawmakers who had written to Bragg requesting that he testify before Congress about his probe.

The Republicans -- who are all chairmen of House committees -- accused Bragg, a Democrat, of waging a "politically motivated prosecution" in their letter dated on Monday.

It was sent after Trump had said on Saturday, without providing any evidence, that he expected to be arrested on Tuesday, and called for supporters to "Protest, take our nation back!"

"Your letter... is an unprecedented inquiry into a pending local prosecution," Leslie Dubeck, the general counsel for Bragg's office wrote in Thursday's response, seen by AFP.

"The letter only came after Donald Trump created a false expectation that he would be arrested the next day and his lawyers reportedly urged you to intervene. Neither fact is a legitimate basis for congressional inquiry," she added.

Trump's post on Truth Social sparked a media frenzy and led to warnings from Democrats that his call for demonstrations could trigger a repeat of the violence his supporters unleashed at the US Capitol on January 6, 2021. Protests have so far been small and sporadic.

New York police have erected barricades outside Bragg's office, Trump Tower and the Manhattan Criminal Court, where Trump would eventually appear before a judge if indicted.

He would become the first former or sitting president to ever be charged with a crime if the grand jury, a panel of citizens convened by Bragg, decides to indict.

The jury was not expected to hear the case Thursday and does not sit on Fridays, meaning any decision would come next week at the earliest.

Bragg is investigating a $130,000 payment to pornographic actress Stormy Daniels in the weeks leading up to the 2016 presidential election.

The payment was allegedly made to stop her from going public about a liaison she says she had with Trump years earlier.

Untested theory

Trump's ex-lawyer-turned-adversary Michael Cohen says he made the payment on his then boss's behalf and was later reimbursed.

If not properly accounted for, the payment could result in a misdemeanor charge for falsifying business records, experts say.

That might be raised to a felony if the false accounting was intended to cover up a second crime, such as a campaign finance violation, which is punishable by up to four years behind bars.

Legal analysts say that argument is untested and would be difficult to prove in court. Any jail time is far from certain.

Trump denies the affair. He repeated on Truth Social Thursday that Bragg has "no case."

Trump is facing several criminal investigations at the state and federal level over possible wrongdoing that threaten his new run at the White House, many more serious than the Manhattan case.

They include his efforts to overturn his 2020 election loss in the state of Georgia, his handling of classified documents, and his possible involvement in the January 6 rioting.

Some observers believe an indictment bodes ill for Trump's 2024 chances, while others say it could boost his support.