Donald Trump and his close personal aide Walt Nauta have pleaded not guilty to the latest allegations in the federal classified documents case.
The fresh charges accuse the two men and a third aide of conspiring to conceal surveillance footage at Mr Trump’s Mar-a-Lago resort from the FBI.
The former president, 77, and Mr Nauta had already pleaded not guilty to previous charges against them.
Mr Trump is fighting on multiple fronts as he mounts his third White House bid.
The documents case is led by Special Counsel Jack Smith, who is also overseeing a separate indictment of Mr Trump over his alleged efforts to overturn the results of the 2020 election.
Mr Smith’s office on Thursday recommended to a federal court in Washington DC that Mr Trump face trial in the election case on 2 January 2024.
In June, he charged the ex-president with 37 counts, for retaining hundreds of confidential files – including about US nuclear secrets and military plans – after leaving office and for lying to investigators.
Mr Nauta, a former Trump White House military valet turned personal aide, was also charged in the indictment and accused of moving files to hide them from the FBI.
In a superseding indictment, prosecutors detailed an alleged effort between Mr Nauta and Carlos de Oliveira, the property manager at Mar-a-Lago, to obstruct the investigation.
The court document alleges the two men, at Mr Trump’s request, tried to delete security footage outside the storage room where documents were being held.
That indictment added one count of wilful retention of defence information and two of obstruction against Mr Trump, bringing the total charges against him in the case to 40.
He had previously waived his right to appear in person in the Florida courtroom on Thursday. His attorney Todd Blanche entered a not guilty plea on his behalf.
Mr Nauta also received two additional charges of obstruction in the latest indictment, while Mr de Oliveira was charged with four counts, including conspiracy to obstruct justice and making false statements.
Both men were present in the room, but Mr de Oliveira was unable to enter a plea as he had not yet retained local counsel. His arraignment has been rescheduled for next Tuesday.
John Irving, a lawyer who represents Mr de Oliveira, did not immediately respond to the BBC’s request for comment. He earlier told ABC News arrangements for local counsel would soon be “ironed out”.
In addition to the charges brought by Mr Smith, Mr Trump also awaits trial on 34 felony counts in a hush-money case in New York, and faces a defamation case from writer E Jean Carroll.
Georgia prosecutors are expected to bring state charges next week over the alleged effort by Mr Trump and several allies to overturn the 2020 election results there.
But Mr Trump has remained popular with Republican voters and remains the frontrunner for the party’s presidential nomination next year.