The former Donald Trump White House aide who became a crucial witness to the January 6 attack says she believes the Republican party is facing a “make-or-break moment” over whether to nominate him in the 2024 presidential race.

“We’re talking about a man who at the very essence of his being almost destroyed democracy in one day, and he wants to do it again,” Cassidy Hutchinson said of Trump during an interview with MSNBC’s Rachel Maddow on Monday, a clear reference to the assault on the US Capitol that the ex-president’s supporters staged after his electoral defeat to his Democratic rival Joe Biden nearly three years ago.

“He wants to run for president to do it again.”

Alluding to the more than 90 charges pending against Trump across four separate criminal indictments, Hutchinson added: “He has been indicted four times since January 6. I would not have a clear conscience and be able to sleep at night if I were a Republican … that supported Donald Trump. And I think that if they’re not willing to split with that, then we’re in serious trouble.”

In a separate notable portion of her interview with Maddow, Hutchinson addressed and summarily dismissed rumors that she had dated Matt Gaetz, the far-right Republican US congressman from Florida who helped spread the claims himself.

“I will say on behalf of myself – I never dated Matt Gaetz,” said Hutchinson, who appeared on Maddow’s show to promote her memoir Enough, hitting bookshelves on Tuesday. Explaining that the pair had an “amicable working relationship” and “were good friends at points”, she added: “I have much higher standards in men.”

Those remarks seemingly build on a cameo from Gaetz in Enough, in which the congressman is shown to unexpectedly take Hutchinson up on an offer to meet several Washington DC political aides out for drinks one night. Later that evening, according to Enough, Gaetz brushes his thumb across Hutchinson’s chin and tells her: “Has anyone ever told you that you’re a national treasure?”

Despite the prominence of men like Trump and Gaetz in her party, Hutchinson reiterated that she still considered herself a Republican, though more in the mold of Senator Mitt Romney or the late president Ronald Reagan, whom some see as more moderate conservatives in retrospect.

“I do not believe that Mr Trump is a strong Republican,” Hutchinson said. “In this election cycle, in my opinion, it’s a make-or-break moment for the Republican party. Now is the time if these politicians [in the party] … want to make the break and want to take the stand – they have to do it now.”

Under subpoena, Hutchinson gave some of the most dramatic testimony about the Capitol attack during live congressional hearings in the summer of 2022. One key moment she described being told about was Trump’s accosting of a Secret Service agent and his lunging for the steering wheel of the car he was in when he was told he would not be driven to the Capitol on the day of the attack.

That wasn’t all she endured that day. In Enough, Hutchinson recounts how on January 6 she was groped by Rudy Giuliani, the Trump lawyer and former New York City mayor.

A short while after Trump told his supporters to “fight like hell”, they mounted the January 6 attack on the Capitol in a desperate but unsuccessful maneuver aimed at preventing Congress from certifying Biden’s victory in the 2020 presidential election weeks earlier.

The uprising has been linked to nine deaths. More than 1,100 people have been charged in connection with the attack, and the majority of them have either pleaded guilty or been convicted by judges or juries at trial.

Trump has pleaded not guilty to all charges filed against him. The various charges collectively accuse him of retaining classified documents after his presidency, hush-money payments to the adult film actor Stormy Daniels, and efforts to subvert his 2020 defeat which led to the January 6 attack.

Despite the legal peril, Trump maintains dominant polling leads over other candidates pursuing the 2024 Republican presidential nomination.

Enough plots out the 27-year-old Hutchinson’s trek from being an earnest believer in Trump to disenchantment with him. She was working for Mark Meadows, Trump’s chief of staff, at the time of the January 6 attack.

Martin Pengelly contributed reporting