President Joe Biden rebuked former President Donald Trump as a “convicted felon” on Monday, telling donors his predecessor “snapped” after losing the 2020 presidential election and would be worse if he won in November.

“For the first time in American history a former president that is a convicted felon is now seeking the office of the presidency,” Biden said at a fundraiser in Greenwich, Connecticut, according to the pool reporter inside the fundraiser. “But as disturbing as that is, more damaging is the all-out assault Donald Trump is making on the American system of justice,” he continued, going on to call Trump “unhinged.”

The remarks, building on comments delivered from the White House following the verdict in Trump’s criminal hush money case in New York, mark the first time Biden has mentioned Trump’s conviction in a campaign setting. The president is refining his campaign trail attacks on the presumptive Republican nominee with less than a month to go until they face off in the first general election debate.

Last week, a Manhattan jury found Trump guilty of all 34 charges of falsifying business records. Speaking to reporters the day after the verdict, Trump repeated his frequent claim that the case had been “all done by Biden and his people,” despite there being no evidence that Biden, his White House aides, or the US Justice Department had any role in Manhattan District Attorney Alvin Bragg’s prosecution.

Asked by a reporter at the White House later that day about Trump’s accusation that he was behind the former president’s conviction, Biden smiled and paused.

“I didn’t know I was that powerful,” he said at the time.