A federal judge referred to US President Joe Biden's handling of sensitive government records as she considered whether to dismiss a criminal case against Donald Trump that charges him with illegally holding onto classified documents.

The remarks by US District Judge Aileen Cannon, who was appointed to her post by Mr Trump, suggested she was comparing the two incidents as she questioned whether the former US president should have known he was breaking the law when he took boxes of sensitive records with him when his presidency ended in 2021.

"It's uncontested that no former executive or former vice president was exposed to criminal liability" other than Mr Trump for allegedly mishandling sensitive government documents, Judge Cannon said at a hearing to consider his arguments that the charges brought by Special Counsel Jack Smith should be dismissed.

However, Judge Cannon indicated she was unlikely to dismiss the case based on Mr Trump's claim that he had deemed the documents to be "personal" rather than government property.

That issue could be addresseduring the trial, she said.

Donald Trump was driven from the Alto Lee Adams Sr courthouse earlier

"Your argument might have some force with respect to a trial defense," she told Mr Trump's lawyers. "It's difficult to see how this gets you to dismissal of the indictment."

The hearing in Fort Pierce, Florida, was the latest legal gambit by Mr Trump to try to derail the four criminal cases he faces while he campaigns as the Republican candidate challenging Mr Biden in the 5 November US election.

Mr Trump has argued that he is the victim of selective prosecution and is being targeted by Democrats as he seeks to regain the presidency.

Prosecutors said that was not true, pointing to the Justice Department's classified documents investigation of Mr Biden.

"We are not puppets of the Biden administration," prosecutor David Harbach said, drawing an audible scoff from Mr Trump.

A federal prosecutor last month said Mr Biden would not face criminal charges for knowingly keeping classified documents at an office and at home after he left the vice presidency in 2017. Mike Pence, who served as vice president under Mr Trump, also was investigated but not charged for keeping classified documents at his Indiana home.

Federal prosecutors who have brought the 40-count indictment against Mr Trump have said his conduct was different.

While Mr Biden and Mr Pence cooperated with investigators, prosecutors have said Mr Trump discussed lying to those who were trying to recover the documents and moved them around his Mar-a-Lago resort to prevent their discovery.

Some of those documents discussed national security issues including nuclear weapons capabilities and US vulnerability to military attack, according to prosecutors.

"Nothing remotely similar to this happened" when other high US officials allegedly mishandled sensitive government records, said Jay Bratt, a prosecutor on the case.

Prosecutors say Mike Pence cooperated when he was investigated for keeping classified documents at his home (file image)

Mr Trump's legal woes have not hampered his political prospects so far, and he clinched the Republican presidential nomination this week.

On Thursday, supporters rallied outside the courthouse, waving banners and cheering as a motorcade pulled into a secure entrance.

At the hearing, Judge Cannon did not seem inclined to agree that the central charge against Mr Trump - illegally retaining information related to US national defense - is improperly vague, as Mr Trump's lawyers have argued.

"That would be an extraordinary step," the judge said.

Mr Trump's lawyers have made five other arguments for dismissal, which could be considered in future hearings that have not yet been scheduled.

The timing of a trial is uncertain. Both Mr Trump and prosecutors acknowledged the currently scheduled May start date will need to be postponed.

Mr Smith has sought a July start, while Mr Trump suggested August even as he argued a trial should not happen before the election.

If Mr Trump wins the presidential election, he would have the power to end the two federal criminal cases, though not the two brought under state law.

Trump hush money prosecutors OK with 30-day delay to New York trial

Mr Trump's legal manoeuvring has yielded some successes in other cases as well.

Prosecutors in Mr Trump's hush money case said they were not opposed to a 30-day delay in the trial, currently set to begin on 25 March, due to a recent disclosure of thousands of pages of documents by federal prosecutors.

The hush money case in New York state court in Manhattan is currently slated to be the first of the four criminal cases Mr Trump faces to reach trial.

While none of the other three cases have firm trial dates, any delay in the New York case could complicate scheduling the other cases.

In a court filing, prosecutors with Manhattan District Attorney Alvin Bragg's office said Mr Trump had requested a 90-day delay to the trial because the Manhattan US Attorney's office - which previously looked into the hush money case - in early March disclosed 73,000 pages of potentially relevant material.

"Although the People are prepared to proceed to trial on 25 March, we do not oppose an adjournment in an abundance of caution and to ensure the defendant has sufficient time to review the new materials," prosecutors wrote.

Mr Trump's request was not immediately available. Any delay would have to be approved by the judge overseeing the case, Juan Merchan.

Prosecutors from Alvin Bragg's office had requested a 90-day delay

Mr Trump has pleaded not guilty to 34 counts of falsifying business records to cover-up hush money paid to adult film actress Stormy Daniels before the 2016 election in exchange for her silence about a sexual encounter she said they had a decade earlier, which he denied.

Earlier this week, Mr Trump asked Judge Merchan to delay the trial until the US Supreme Court finishes its review of his claim of presidential immunity in his federal criminal case over efforts to overthrow his 2020 election loss to Biden.

The Supreme Court is slated to hear those arguments on 25 April.

An election subversion case in Georgia state court has been thrown into limbo as a judge considers whether to remove the lead prosecutor for having a romantic relationship with a subordinate.

A 30-day delay to the hush money trial would mean it would start that same week - a little over six months before the election.