The US Justice Department has said that Donald Trump can be held personally liable for his comments about a woman who accused him of rape, in a reversal of its position that Trump was protected because he was president when he made the remarks.

In a letter on Tuesday, the department said it no longer has “a sufficient basis” to conclude that Trump was motivated in his statements about writer E Jean Carroll’s claims by more than an insignificant desire to serve the United States.

The letter was filed with a federal district court judge presiding over a 2020 defamation lawsuit brought by Carroll in Manhattan.

Previously, the department had agreed with Trump’s lawyers that he was protected by the Westfall Act, which provides federal employees absolute immunity from lawsuits brought over conduct occurring within the scope of their employment.

In May, a jury awarded Carroll $5m in damages after concluding that Trump sexually abused her in 1996 at a midtown Manhattan Bergdorf Goodman store and then defamed her last fall with comments he made about her and her claims. While the jury found Trump liable for sexually abusing Carroll, it rejected her rape claim.

The trial resulted from a lawsuit Carroll brought last November after New York state temporarily allowed victims of sexual abuse to make civil claims for attacks that occurred even decades earlier.

In Tuesday’s letter, US lawyers cited the jury’s verdict, Trump’s October deposition and new claims Carroll has made that Trump defamed her again with comments during a CNN town hall forum a day after the verdict.

The letter gives fresh fuel to Carroll’s original defamation lawsuit, which had been delayed by appeals over whether Trump could be held liable for statements he made while president.

The original claims are scheduled for trial next January and stem from comments Trump made in 2019, after Carroll first went public about the alleged sexual abuse in a memoir.

Carroll’s lawyer, Robbie Kaplan, welcomed the Department of Justice’s submission, saying it was one of the “last obstacles” to the lawsuit reaching trial.

“We are grateful that the Department of Justice has reconsidered its position,” she said in a statement. “We have always believed that Donald Trump made his defamatory statements about our client in June 2019 out of personal animus, ill will, and spite, and not as President of the United States.”

Lawyers for Trump did not immediately comment.

Earlier in the day, Carroll’s lawyers filed papers challenging a counterclaim in the defamation lawsuit by Trump’s lawyers. They maintained that Carroll had also defamed him with comments she made after the May verdict — in part because she repeated statements that he had raped her.

Her lawyers wrote that his counterclaim was “nothing more than his latest effort to spin his loss at trial”.

They said the sexual abuse Trump was found liable for was equivalent to rape under some criminal statutes and would require him to register for the rest of his life as a sex offender if it had been a criminal claim.

The Associated Press typically does not name people who say they have been sexually assaulted unless they come forward publicly, as Carroll has done.