And if history is any indication, the conservative wing of the Kentucky GOP is gaining momentum.
In 2010, Sen. Rand Paul's libertarian message resonated enough with voters to secure his victory against McConnell's establishment pick in the U.S. Senate race.
McConnell knows the vulnerabilities. He hired Ron Paul presidential campaign spokesman and Rand Paul's campaign manager Jesse Benton to run his 2014 campaign in an effort to bring together moderate and conservative Republicans to support McConnell.
McConnell's campaign did not return a request for comment.