Democratic presidential hopeful former US Vice President Joseph R. Biden Jr. speaks during the second Democratic primary debate of the 2020 presidential campaign season hosted by NBC News at the Adrienne Arsht Center for the Performing Arts in Miami, Florida, June 27, 2019.

Former Vice President Joe Biden lost one of his top fundraisers after controversial comments regarding his work with past segregationists and his flip-flop on repealing the Hyde Amendment, CNBC has learned.

Tom McInerney, a veteran San Francisco based lawyer, informed Biden's team on June 20 that he can no longer help him raise campaign cash to compete in the 2020 presidential election.

"I had actually let the campaign known I'd pulled back my support of Biden for now," McInerney told CNBC. "I don't think he did well last night," he added, reflecting on Biden's debate performance on Thursday night.

While McInerney is the first financier to publicly withdraw his support after Biden's controversial round of comments, the loss is significant because it could be a harbinger of further defections.

"I would imagine I'm not alone," said McInerney, who was a lead bundler for President Barack Obama in his first run for president. He helped Obama's campaign raise at least $200,000 throughout that cycle, according to the nonpartisan Center for Responsive Politics.

The news comes as Biden is starting a Bay Area fundraising tour on Friday that will continue through the weekend.

Biden's campaign has been reeling from his latest stumbles.

At a recent fundraiser, Biden recalled his days as a senator from Delaware, working alongside two segregationist lawmakers, including Sen. James Eastland, D-Miss.

"At least there was some civility. We got things done. We didn't agree on much of anything," Biden said at the time. "Today, you look at the other side and you're the enemy."

Earlier this month, Biden went back and forth publicly over whether he supported the Hyde Amendment, which bars federal funding for most abortions. He eventually declared he was against the law.

A spokesperson for Biden did not return a request for comment.