Senate Minority Leader Mitch McConnell (R-Ky.) will face a primary challenger from the right in Matt Bevin, a local businessman and Tea Party candidate who plans to announce his run for Senate this week.
Bevin, who has been exploring the race since February, is reportedly already buying airtime and has met with multiple conservative groups about his run. He'll launch a 3-day, 8-stop tour of the state after he formally announces his campaign on Wednesday.
His personal wealth would be an advantage running against McConnell, who has nearly $10 million cash on hand for the race.
McConnell has long been considered vulnerable to a primary challenge.
The Kentucky senator has worked, in recent years, to shore up support on his right flank and hired Jesse Benton, the former campaign manager for Sen. Rand Paul (R-Ky.) with ties to the Tea Party in Kentucky, to his team.
Democrats believe McConnell to be vulnerable heading into 2014, citing polling that shows him unpopular in his state.
They also got their preferred remaining candidate in Kentucky Secretary of State Alison Lundergan Grimes, after a handful of other Democrats passed on the race.