A person with knowledge of the move confirmed that Josh Holmes, McConnell's chief of staff in his Senate office, is stepping down on Wednesday.

The source said that Republicans see the 2014 cycle as one of their last chances for a long time for Republicans to retake control of the Senate.  

"And Holmes is one of those unique talents who can make a big difference in the effort to make that happen. Really smart move," the source said.

Holmes previously worked at the NRSC. He is likely to return to McConnell's office if the minority leader wins reelection.

McConnell is facing a reelection challenge from state Sen. Alison Lundergan Grimes (D) and Tea Party challenger Matt Bevin.

A new poll by the Democratic leaning Public Policy Polling released Thursday found McConnell and Grimes in a near perfect dead heat. The poll found Grimes leading McConnell 45 percent to 44 percent.