Patterson said in a statement that he's running because voters want an "alternative" to McConnell, according to The Associated Press.

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 PaulRandal (Rand) Howard PaulGOP senators call for probe of federal grants on climate change Overnight Health Care — Presented by the Association of American Medical Colleges — Key ObamaCare groups in limbo | Opioids sending thousands of kids into foster care | House passes bill allowing Medicaid to pay for opioid treatments US watchdog: 'We failed' to stem Afghan opium production MORE (R-Ky.).