Bevin's campaign did not immediately explain why Semmel left the campaign but according to WFPL's Phillip Bailey, Semmel had decided to move back to Washington, D.C.
"Rachel has moved back to D.C. to pursue another career opportunity,” says @MattBevin spox Sarah Durand. #KYSen
— Phillip M. Bailey (@phillipmbailey) April 21, 2014
A few days earlier news broke that Amy Kremer had resigned as the chairwoman of the Tea Party Express to join the Bevin campaign. According to CNN, Kremer would do consulting work for Bevin.
WFPL also noted that two field operatives also left Bevin's campaign recently.
A week ago McConnell announced that he had raised $2.4 million in the first quarter of 2014 and had $10.4 million cash on hand. Bevin, meanwhile, raised $1.12 million over the same period. A pair of February polls, one of which was conducted by a pro-McConnell super PAC, found McConnell leading his primary challenger by 38 to 41 percentage points.
The Kentucky Republican primary is on May 20.
This post was updated.