Top aides to former President Joe Biden privately urged major donors not to support replacing him with his chosen vice president, warning it would be a serious “mistake,” according to excerpts from an upcoming book previewed by The Guardian on Thursday.

The book, “Fight: Inside the Wildest Battle for the White House,” by NBC News’ Jonathan Allen and The Hill’s Amie Parnes, reveals how Biden’s team “aggressively” lobbied top Democratic donors to stick with the president as he fought to salvage his candidacy in the summer of 2024.

In the wake of Biden’s disastrous debate performance in late June, the book details internal efforts to cast doubt on Vice President Kamala Harris’s viability as a replacement as part of a desperate push to retain the nomination.

As pressure rose on Biden to step away from his reelection bid following the debate, Biden aides “frantically push[ed] back in phone calls and in text messages, accusing donors of promoting their own agendas at the expense of Biden, the party, and the country,” Allen and Parnes write in their book. “It all sounded like a serial killer’s conspiracy theory,” the authors write, before switching to italics to denote the thoughts and descriptions of sources who spoke to them about their own internal thoughts and private discussions:

“‘Donors want to scrap Biden so they can get his wannabe replacements – the governors, with power over state decisions – to beg them for cash,’ Biden aides argued. ‘This isn’t f**king Wall Street financiers versus Ivy League presidents. Our guy isn’t scared of your money. We have grassroots donors. We have the support of the voters. We have the nomination in hand. All you’re doing is f**king yourself and the president. We will remember this. Capisce?’”

“The last threat, the ace in the hole, was Kamala Harris,” the authors wrote. “Even if Biden did drop out and you got your dreamed-up open convention, you would only succeed in nominating the vice-president. Is that what you want? You want her? Look at her polling. No one wants her. Forget it. It’s never gonna happen.”

In the weeks following his historically poor debate performance, Biden’s aides and allies continued to argue that he remained capable of winning the general election. They emphasized that he was the only Democrat who had previously defeated President Donald Trump—and could do it again.

Despite their efforts, Biden ultimately exited the race on July 21, facing a fundraising freeze and mounting public pressure from Democratic leaders and party insiders to step aside.