A judge has rejected president-elect Donald Trump's bid to have his "hush money" conviction dismissed because of the US Supreme Court's recent ruling on presidential immunity.

Manhattan Judge Juan M Merchan's decision on Monday eliminates one potential off-ramp from the case ahead of Trump's return to office next month, but his lawyers have raised other arguments for dismissal.

Prosecutors have said there should be some accommodation for his upcoming presidency, but they insist the conviction should stand.

A jury convicted Trump in May of 34 counts of falsifying business records related to a $US130,000 ($204,000) hush money payment to porn actor Stormy Daniels in 2016.

Trump has denied any wrongdoing.

The allegations involved a scheme to hide the payout to Daniels during the final days of Trump's 2016 presidential campaign to keep her from publicising — and keep voters from hearing — her claim of a sexual encounter with the married then-businessman years earlier.

He says nothing sexual happened between them.

A month after the verdict, the Supreme Court ruled that ex-presidents could not be prosecuted for official acts — things they did in the course of running the country — and that prosecutors could not cite those actions to bolster a case centred on purely personal, unofficial conduct.

Trump's lawyers then cited the Supreme Court opinion to argue that the hush money jury got some improper evidence, such as Trump's presidential financial disclosure form, testimony from some White House aides and social media posts made while he was in office.

Evidence related to official acts, Trump says

In Monday's ruling, Judge Merchan denied the bulk of Trump's claims that some of the prosecutors' evidence related to official acts and implicated immunity protections.

The judge said that even if he found that some evidence related to official conduct, he would still conclude that prosecutors' decision to use "these acts as evidence of the decidedly personal acts of falsifying business records poses no danger of intrusion on the authority and function of the Executive Branch".

Even if prosecutors had erroneously introduced evidence that could be challenged under an immunity claim, Judge Merchan continued, "such error was harmless in light of the overwhelming evidence of guilt".

Prosecutors had said the evidence in question was only "a sliver" of their case.

Trump communications director Steven Cheung on Monday called Judge Merchan's decision a "direct violation of the Supreme Court's decision on immunity, and other longstanding jurisprudence".

"This lawless case should have never been brought, and the constitution demands that it be immediately dismissed," Mr Cheung said in a statement.

Manhattan District Attorney Alvin Bragg's office, which prosecuted the case, declined to comment.

Judge Merchan's decision noted that part of the Supreme Court's immunity ruling declared that "not everything the president does is official".

Trump's social media posts, for example, were personal, Judge Merchan wrote.

He also pointed to a prior federal court ruling that concluded that the hush money payment and subsequent reimbursements pertained to Trump's private life, not official duties.

Efforts to get conviction dismissed

Trump is the first former president to be convicted of a felony and the first convicted criminal to be elected to the office.

Over the last six months, his lawyers have made numerous efforts to get the conviction and the overall case dismissed.

After Trump won last month's election, Judge Merchan indefinitely postponed his sentencing — which had been scheduled for late November — so defence lawyers and prosecutors could suggest next steps.

Trump's defence argued that anything other than immediate dismissal would undermine the transfer of power and cause unconstitutional "disruptions" to the presidency.

Meanwhile, prosecutors proposed several ways to preserve the historic conviction, including freezing the case until Trump leaves office in 2029, agreeing that any future sentence would not include jail time, or closing the case by noting he was convicted but that he was not sentenced and his appeal was not resolved because he took office.

The last idea is drawn from what some states do when a defendant dies after conviction but before sentencing.

Trump's lawyers branded the concept "absurd" and took issue with the other suggestions, too.

Trump was indicted four times last year.

The hush money case was the only one to go to trial.

After the election, special counsel Jack Smith ended his two federal cases.

They pertained to Trump's efforts to overturn his 2020 election loss and allegations that he hoarded classified documents at his Mar-a-Lago estate.

A separate state election interference case in Fulton County, Georgia, is largely on hold.

Trump denies wrongdoing in all.

AP