Jeb Bush’s decision to attack old friend and new rival Marco Rubio is backfiring, pushing important supporters to criticize the campaign’s tactics and driving one of Florida’s top fundraisers to officially quit and signal a shift in allegiance to the senator.

“I think the world of Jeb Bush. He was a great governor of Florida and is a really good person, but the campaign has hijacked his message” said Brian Ballard, a Tallahassee lobbyist who contributed more than $25,000 of his own money and has raised hundreds of thousands of dollars more for Bush’s campaign and the super PAC supporting him.

“The campaign has become negative, one that is about attacking and trying to bring down Marco Rubio. And that doesn’t sit well — not only with me, but with anyone who knows the two,” Ballard said. “Marco’s a friend of mine. I didn’t sign up for a campaign that was going to be negative and attack a bright star of the party’s future. It doesn’t make sense. I’m over it. And I’m done.”