Tea Party Express Chairman Amy Kremer resigned Friday to join the campaign of Matt Bevin, who's challenging Senate Minority Leader Mitch McConnell in the May 20 Kentucky Republican primary.

"I've wanted to move in a different direction for a while, but also wanted to make sure that any change I make was also a positive change for the conservative movement," Kremer wrote in a Facebook post.

“As one of the only remaining members of the original tour, Tea Party Express has been a huge part of my life and I am proud of the historic work we accomplished — like partnering with CNN to host the first ever Tea Party Presidential Debate and electing conservatives such as Senators Mike Lee and Ted Cruz to Congress," Kremer wrote.

Kremer believes those senators are being thwarted by McConnell. "They're having daggers put in their back, not by the Democrats but by members of their own caucus,” she told CNN. “That effort is being led by Mitch McConnell and the only way to stop that is to defeat Mitch McConnell."

Kremer's move comes at a time when Bevin's campaign is struggling. "Matt Bevin fell early to a barrage of negative attacks defining him before he could define himself," RedState's Erick Erickson wrote Wednesday. "He is far down with a month to go. While he benefits from a wave of conservative grassroots support, including my own here at RedState, he has much ground to make up and little time to do it. Short of a nonstop very positive media campaign re-defining himself, Bevin is not going to win. The voters in Kentucky may not care for Mitch McConnell. Conservative activists around the country may not care for McConnell. But Bevin has failed thus far to present a compelling, positive narrative of himself and why he should be the guy to replace Mitch McConnell. With early voting approaching, he has less than one month to do that."