Senate Minority Leader Mitch McConnellMitch McConnellSenate Dem: We’re trying to block a recess appointment to replace Sessions Trump predicts 'problems' for those voting against ObamaCare repeal Overnight Defense: House passes Russia sanctions deal | McCain returns to Senate | Watchdog opens criminal probe into M camo mistake MORE's (R-Ky.) Tea Party challenger has lost a top staffer with just one month to go before the Kentucky primary, according to a local radio station.

Rachel Semmel, businessman Matt Bevin's top spokeswoman, is no longer with his campaign, WFPL reports. 

"Rachel has moved back to D.C. to pursue another career opportunity and is no longer with the campaign," Bevin spokeswoman Sarah Durand told WFPL. "The Bevin campaign is grateful for all she did for the team and wishes Rachel the best in her future endeavors."

Semmel left Rep. David SchweikertDavid SchweikertFreedom Caucus backs three debt ceiling options Bipartisan lawmakers give blood in honor of Scalise GOP senators pleased with Ivanka Trump meeting on family leave, child tax credits MORE's (R-Ariz.) office last year to join Bevin's staff. 

WFPL also reported at least two field operatives have also recently left Bevin's campaign. 

The development is a setback for Bevin's campaign as he seeks to make up ground on McConnell, who has led by wide margins in the few public polls of the primary.