BOSTON — President Joe Biden struck back at Donald Trump on Tuesday, warning that democracy is “more at risk in 2024” and telling donors that the former president and his allies are determined to “destroy” democratic institutions.

Biden’s forceful rhetoric against Trump came as the current GOP frontrunner, who tried to overturn Biden’s 2020 election victory and is facing criminal charges connected to those efforts, attempted over the weekend to turn the tables against him by calling Biden the “destroyer of American democracy.”

But during a campaign fundraiser in Boston, Biden warned of what is at stake if Trump regains the presidency, noting that he has described himself as his supporters’ “retribution” and that he has vowed to root out “vermin” in the country.

Biden, who said he is not alone in sounding the alarm, noted that Trump is the “only losing candidate” in U.S. history to not accept the results. Biden also said that during the Jan. 6, 2021, insurrection at the Capitol, Trump sat in his dining room just off the Oval Office, “watching them threaten his own vice president.”

Biden also highlighted recent warnings about Trump from former Rep. Liz Cheney, R-Wyo., calling her a “powerful voice.”

“American democracy, I give you my word as a Biden, is at stake,” the president said Tuesday at the first of three campaign fundraisers in the Boston area. Drawing some laughter from donors, Biden also mused: “He didn’t even show up at my inauguration. I can’t say I was disappointed, but he didn’t even show up.”

The event is part of Biden’s big push to raise money for his reelection effort before the end of the year, appearing at seven events through Monday — with more to come. The events in Boston on Tuesday, which will benefit his campaign and the broader Democratic Party, includes an evening event in the city’s theater district featuring a concert by singer-songwriter and guitarist James Taylor.

Later this week, the Democrat will touch down on the West Coast on Friday for his first Los Angeles fundraisers since the end of the strikes by actors and screenwriters, featuring film director Steven Spielberg and “Scandal” showrunner Shonda Rhimes, among other celebrities.

Biden will also attend a fundraiser Wednesday near the White House and another one on Monday in Philadelphia.

“This next election is going to be different,” the president said last week at a money event in Denver, where he sought to draw contrasts with former President Donald Trump, expected to be his Republican opponent. “Not because I’m running, because of the nature of what’s at stake.”

The burst of fundraising comes as the holiday season sets in and as candidates make their final pushes to raise needed cash before the quarter ends on Dec. 31.

Biden is also headlining fundraisers in Washington, D.C., and in Maryland later in December.

November was the campaign’s strongest grassroots fundraising month since Biden formally announced last April that he was seeking a second term, according to a campaign official who insisted on anonymity to discuss campaign finances before details are made public.