At fund-raising events where he has pulled in more than $24 million for Joseph R. Biden Jr.’s campaign in the past two months, former President Barack Obama has privately unleashed on President Trump to party donors, bringing up past accusations of Mr. Trump’s “assaulting women” and warning of his efforts to push “nativist, racist, sexist” fears and resentments.
With less than 100 days until the presidential election, Mr. Obama has laid out the stakes of 2020 in forceful fashion. He has urged support for Mr. Biden, his former vice president, while worrying about the state of American democracy itself, even making an oblique reference to Nazi Germany, according to notes made from recordings of Mr. Obama’s remarks, donors and others who have been on the calls.
Even three years out of office, Mr. Obama remains one of the Democratic Party’s biggest draws for giant contributors and small donors alike. A virtual conversation on Tuesday with the actor George Clooney sold out of tickets that ranged from $250 to as much as $250,000. (The biggest donors got access to a small “virtual clutch” with Mr. Obama.)
Donors who have paid six-figure sums to see Mr. Obama on Zoom — he held two other, more intimate, conversations for donors with Reid Hoffman, the founder of LinkedIn and a major Democratic donor, and J.B. Pritzker, the billionaire governor of Illinois — have been privy to wide-ranging Q. and A. sessions about the state of politics and unvarnished analysis from the former president.
On Tuesday evening, during the event with Mr. Clooney, Mr. Obama was asked what keeps him up at night these days. He cited fears of voter suppression and an effort by Mr. Trump to question the election’s legitimacy.
Mr. Obama, who has carefully calibrated his public statements since leaving office to avoid being pulled into one-on-one combat with a current president looking for a foil, is considerably more caustic when the cameras are off, according to people who have been on the calls and notes made from recordings.
During his conversation with Mr. Pritzker, Mr. Obama spoke about how Mr. Trump has a core base that “filters out any contradictory information.”
“It’s just glued to Fox News and Breitbart and Limbaugh and just this conservative echo chamber — and so, they’re going to turn out to vote,” Mr. Obama said. “What he has unleashed and what he continues to try to tap into is the fears and anger and resentment of people who, in some cases, really are having a tough time and have seen their prospects, or communities where they left, declining. And Trump tries to tap into that and redirect in nativist, racist, sexist ways.”
Mr. Obama’s office did not dispute his private comments but declined to comment further.
The former president dismissed Mr. Trump’s continued focus on the Confederate monuments as a distraction amid the coronavirus pandemic — “that’s like his No. 1 priority” — but also characterized it as a menace that “gives you a sense of what this is about.” He then pivoted to what those “darker impulses” have wrought in history.
“The endpoint of that we saw in Europe 60 years ago, 70 years ago — what happens when those things get unleashed,” Mr. Obama said, according to the notes. “You don’t nip that in the bud, bad things can happen. Among the most quote unquote civilized societies.”
During the event with Mr. Hoffman, Mr. Obama called out Mr. Trump for stoking “anti-Asian sentiment” when talking about the virus, which the president has called the “kung flu” and “Chinese virus.”
“That still shocks and pisses me off,” Mr. Obama said. He went even further as he told the virtual crowd that he hoped his seriousness of purpose was emanating through the screen.
“We already saw this guy win once,” he said. “After he bragged about physically assaulting women — and that didn’t seem to matter. So, enough said. Let’s get to work.”
Mr. Obama sat firmly on the sidelines during the Democratic primary race but has mobilized to help his former vice president. In addition to the four virtual events — his joint appearance with Mr. Biden is still the campaign’s single biggest fund-raising event — he has lent his name to digital solicitations that are among the party’s highest-performing missives.
And Mr. Obama and Mr. Biden’s “socially distanced” video released last week not only earned airtime on television news, but was also an organizing tool for the campaign, which tripled email sign-ups in the 24 hours after its initial release, compared with the day before.
At the Democratic National Committee, the times that Mr. Obama signs emails have been known internally as “Barack Obama days” for the influx of contributions and for a reactivating effect among supporters.
“He’s obviously one of our most effective surrogates,” said Tom Perez, the D.N.C. chairman, who hailed the efficiency of virtual fund-raisers and moderated the conversation between Mr. Obama and Mr. Hoffman.
“The virtual context means you don’t have to put him and other surrogates on a plane,” Mr. Perez said. “This just allows him to do more events, more efficiently. That’s been a surprise.”
Mr. Obama is still said to be concerned that appearing in too many virtual fund-raisers will blunt his impact over time — but he recently told a former campaign aide that they were far easier than he expected, taking only about an hour of his time, requiring no travel and providing a cash return for the Biden team that exceeded his expectations.
Mr. Obama’s first fund-raising appearances with Mr. Biden raised $11 million, including $7.6 million from smaller online contributors and $3.4 million from big donors who got a more private session with the two men, according to the Biden campaign. The Hoffman event raised $5.6 million and the Pritzker event more than $3 million, according to people familiar with the matter.
In his private fund-raisers, Mr. Obama has praised Mr. Biden’s character and hailed him as a future “great president,” almost turning the tables on donors and others who have tried to offer “constructive criticism” to the Biden campaign given the stakes of the election.
“We have a worthy candidate and we have a worthy platform,” Mr. Obama said. “But you know what, let’s not be so sophisticated that we are constantly finding reasons why this isn’t good enough or the candidate’s not doing this or the campaign seems to not be getting that quite right.”
D.N.C. officials and Biden campaign aides have tried, gingerly, to enlist Michelle Obama to appear in her own online fund-raisers. But the former first lady, who has been focusing her energy on other projects like a new podcast, has told people in her orbit that she does not consider herself a political player. She has committed to virtually appearing at the Democratic National Convention but signaled she would engage more in the campaign at a time and in a fashion of her choosing.
So far, Mrs. Obama has neither headlined high-dollar fund-raisers nor signed messages to email lists for Mr. Biden and the D.N.C.
In a window into the Obamas’ contrasting approaches, Mr. Obama tweeted a link on Sunday to the Democratic Party’s voter registration portal, noting that it was 100 days until the election. That tweet, along with a link by the model Kendall Jenner to her 135 million Instagram followers, drove more than 100,000 visitors.
That day — within minutes of Mr. Obama’s post — Mrs. Obama also posted a video urging people to register to vote on Twitter. But she linked to her own nonpartisan nonprofit, When We All Vote.
“Where we disagree is usually you just think things just have to get super, super bad before folks figure stuff out,” Mr. Obama told Mrs. Obama on her podcast, which debuted on Wednesday.
“Well, I hope we’re at that point,” she said, before adding, “We’ll figure it out before we crash into the sun.”
Mrs. Obama’s office declined to comment.
Mr. Clooney, appearing on Tuesday in a blazer and an unbuttoned white dress shirt, framed this year’s election as a simple choice.
“Like, this is easy,” he said. “There’s two candidates here. One claims that our first Black president wasn’t a citizen, and the other was his vice president.”