Updated 10:14 a.m. ET, 4/18/2014
(CNN) - Amy Kremer, the Tea Party Express chairman who's played a major role in elections for the past five years, is resigning.
"This has been a really difficult decision for me, but the time has come for me to leave Tea Party Express," Kremer said Friday.
The group is one of the largest and most politically active national tea party organizations. It got its start in 2009 as a bus tour that crisscrossed the country multiple times as it held rallies and supported conservative candidates.
In the 2012 election cycle, the group partnered with CNN to host the first tea party Republican presidential debate.
The timing of her departure comes as the Tea Party Express plans to spend four days in Florida’s 19th Congressional District to support conservative Curt Clawson in a special election.
But Kremer says she doesn’t want to dedicate her time to a district that already leans Republican and on a race that will have to take place again in November.
Instead, Kremer will be doing consulting for businessman Matt Bevin, who’s challenging Senate Republican Leader Mitch McConnell in Kentucky’s GOP primary on May 20.
“This should be ground zero for the movement,” Kremer told CNN. “A U.S. senator definitely has more of an impact on our debt than a congressman that potentially will spend eight months in Washington, and my heart tells me that I should be on the ground focused on competitive Senate races.”
Still, Kremer described her split with Tea Party Express as amicable.
“The Tea Party Express doesn't plan to come here (Kentucky), and that's OK. I made this decision, it was time, and I am where I am,” she said. “I wish Tea Party Express all the best, but it was time to move on.”
She compared Bevin to other conservatives in the Senate who have bucked the GOP establishment, such as Sens. Ted Cruz, Rand Paul and Mike Lee.
“They're having daggers put in their back, not by the Democrats but by members of their own caucus,” she said. “That effort is being led by Mitch McConnell and the only way to stop that is to defeat Mitch McConnell.”
While polls show the five-term incumbent has a sizable polling and fundraising advantage, Bevin enjoys the support of major outside conservative groups.
Kremer also plans to get involved in GOP primaries in Kansas, North Carolina, and Mississippi—the latter of which is considered the most likely for the sitting incumbent to lose his seat to a challenger. Mississippi state Sen. Chris McDaniel is running against six-term Sen. Thad Cochran.
“When Thad Cochran went to Washington, I was in diapers,” Kremer said. “You give these men six more years, what are they going to do in six more years that they haven't already been given an opportunity to do?”
She added she's confident Republicans can take back control of the Senate, and while she "may not be on a bus" anymore, she's still be "working on the same thing I've been working on the past five years."