A federal prosecutor in the classified documents case of former US president Donald Trump clashed with the judge on Monday as he faced skeptical questioning over a request to bar the former president from making threatening comments about law enforcement agents involved in the investigation.

Special counsel Jack Smith’s team is seeking to make as a condition of Trump’s freedom pending trial a prohibition on remarks that could endanger FBI agents participating in the case. Prosecutors say those restrictions are necessary after Trump falsely claimed last month the FBI was prepared to kill him when it searched his Florida estate, Mar-a-Lago, for classified documents two years ago.

But prosecutor David Harbach, a member of Smith’s team, encountered immediate pushback from US District Judge Aileen Cannon, a Trump appointee whose handling of the case has generated intense scrutiny and contributed to delays that make a trial before the November presidential election a virtual impossibility.

The judge questioned Harbach about how she could fashion an order that did not run afoul of Trump’s free speech rights, whether FBI agents were sufficiently protected if their names were withheld from court documents and how prosecutors could prove a direct link between Trump’s comments and any resulting harm to the public.

“I’m trying to make sure that whatever condition is contemplated is consistent with the First Amendment,” she said, later adding that there needs to be a connection “between the alleged dangerous comments and the risk” to public safety.

At one point, as Harbach tried despite frequent interruptions from Cannon to rattle off the multiple rationales he said existed for speech restrictions on Trump, the visibly exasperated prosecutor noted acidly that “I’ve got one reason out so far”.

The comment drew a rebuke from Cannon, who said, “Mr Harbach, I don’t appreciate your tone.” She said if he could not behave in a more professional manner, one of his colleagues could take over instead.

Harbach went on to complete his arguments and later apologised to the judge, saying he hadn’t meant to be unprofessional.

Defence lawyer Todd Blanche disputed the idea Trump’s comments posed an imminent threat to anyone in law enforcement and contended that the prosecutors’ request would have a chilling effect. Trump is the presumptive Republican presidential nominee and is set to debate US President Joe Biden on Thursday.

US President Joe Biden pictured at a meeting with Nato Secretary-General Jens Stoltenberg. Photo / AP

Trump was not required to be present for the hearing and was not in attendance.

Trump’s often-incendiary rhetoric has carried legal consequences in other cases.

The New York judge presiding over Trump’s hush money trial, in which he was convicted of 34 felony counts last month, fined him a total of $10,000 for violating a gag order that barred him from verbal attacks on witnesses and jurors. And a federal judge in Washington handling his election subversion case imposed a gag order last year that an appeals court later largely upheld but also narrowed.

It was not immediately clear when Cannon might rule. The arguments were part of a three-day hearing that began on Friday to deal with several of the many unresolved legal issues that have piled up in a case that has been snarled by delays and a plodding pace. Cannon indefinitely postponed the trial last month and no new date has been set.

Trump faces dozens of felony charges accusing him of illegally hoarding top-secret records at Mar-a-Lago and obstructing the FBI’s efforts to get them back. Given the breadth of evidence prosecutors have put forward, many legal experts have regarded the case as the most straightforward of the four prosecutions against Trump, who has pleaded not guilty. But Cannon has been slow to rule on numerous motions and proved willing to entertain defence requests prosecutors say are meritless.

Smith’s team objected last month after Trump publicly claimed the FBI was prepared to kill him while executing a court-authorised search warrant of Mar-a-Lago on August 8, 2022. Trump was referencing boilerplate language from FBI policy that prohibits the use of deadly force during the execution of search warrants except when the officer conducting the search has a reasonable belief that the “subject of such force poses an imminent danger of death or serious physical injury to the officer or to another person”.

Trump falsely claimed in a fundraising email that the Biden administration was “locked & loaded ready to take me out & put my family in danger [sic]”.

Prosecutors argued such comments are part of a pattern of Trump speech that animates his base against law enforcement, citing as examples an attempted attack on an FBI office in Ohio three days after the Mar-a-Lago search and the more recent arrest of a Trump supporter accused of threatening an FBI agent who investigated Biden’s son, Hunter.

“In our view, they are significant, they are dangerous,” Harbach said of the comments. “They present an imminent and foreseeable risk to the FBI agents in the case.”

But Trump’s lawyers say prosecutors failed to show his comments have endangered any FBI official who participated in the Mar-a-Lago search. They said Trump was commenting more generally on his belief he is the victim of political persecution rather than any one individual.

Supporters of former US president Donald Trump gather along Southern Boulevard outside Mar-a-Lago in Palm Beach, Florida. Photo / AP

“It’s an attack on the decision made by his political rival to authorise a search by agents authorised to carry guns,” said Blanche, one of Trump’s attorneys.

The Justice Department has said Biden has had no involvement in the investigation.