A NEW YORK judge has ruled against a bid by US President-elect Donald Trump to have his conviction for covering up hush money payments to a porn star thrown out on immunity grounds.

In July, the country’s top court ruled that presidents have broad immunity from criminal prosecution for “official actions” they take while in office.

But on Monday, Manhattan Judge Juan Merchan – who presided over Trump’s trial this past spring – sided with prosecutors, saying the convictions on 34 felony counts centred on “unofficial conduct”.

The ruling raises the prospect that Trump could become the first president to enter the White House with a felony conviction, pending his appeal against the jury’s verdict.

Trump has sought to have the case moved to federal court, which would give him the power to end the case himself as soon as he retook the presidency.

He has also challenged the conviction on a number of technical grounds, including alleging juror misconduct.

Trump has long opposed the criminal process brought against him after he paid porn star Stormy Daniels for her silence over an alleged sexual encounter, and then covered up the payments in an effort to boost his chances in 2016′s election.

A month after the verdict, the supreme court ruled that ex-presidents can’t be prosecuted for official acts – things they did in the course of running the country – and that prosecutors cannot cite those actions to bolster a case centered 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.

In his ruling, Merchan denied the bulk of Trump’s claims that some of 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’d still find 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”.

He was originally due to be sentenced on 26 November, but Judge Merchan postponed it indefinitely after Trump won the US election.

If the conviction stands, sentencing may not take place until after he finishes his second stint in the White House in 2029.