McConnell already faces multiple challengers from the left and right. Conservative Matt Bevin has launched a Tea Party-backed primary bid, while Kentucky Secretary of State Alison Lundergan Grimes is running for, and will likely receive, the Democratic nomination.
Democrat Ed Marksberry is also pursuing his party's nomination, but he's unlikely to gain much momentum.
While Patterson, too, isn't expected to cause too much damage to McConnell, the ever-expanding field is a reflection of how vulnerable observers believe the senator to be.
Polling has shown him to be unpopular in Kentucky, and despite his standing as one of the most powerful Republicans in Washington, Democrats and conservatives — as well as, as Patterson has shown, libertarians — in Kentucky and nationally believe they have an opportunity to take him down in 2014.
McConnell, however, has the backing of one of the state's most prominent Tea Party and libertarian voices — Sen. Rand Paul (R-Ky.).
Libertarian lines up to challenge McConnell
Patterson said in a statement that he's running because voters want an "alternative" to McConnell, according to The Associated Press.