Matt Bevin, the Tea Party-backed candidate challenging Senate Minority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellSenate passes 0B defense bill Overnight Health Care: New GOP ObamaCare repeal bill gains momentum Overnight Finance: CBO to release limited analysis of ObamaCare repeal bill | DOJ investigates Equifax stock sales | House weighs tougher rules for banks dealing with North Korea MORE (R-Ky.) for the Republican nomination in the Kentucky Senate race, has won the endorsement of the president of the Louisville Tea Party.

It's the latest indication Bevin is picking up steam against McConnell. He's also gotten the backing of a number of other Kentucky Tea Party groups, and the endorsement of the Madison Project, which supports conservative candidates nationwide.

In an op-ed in the Courier Journal, Louisville Tea Party President Wendy Caswell contrasts McConnell, who she says "go[es] along to get along," with "principled" Bevin.

"Sen. Mitch McConnell represents the old guard in Washington, D.C., that cares more about holding on to power than defending the principles of limited government, fiscal responsibility and individual freedom," she writes.

She adds: "Those are the principles that Bevin believes in. I know he believes in those fundamental conservative ideals because he has embodied them in his life’s experiences."

Caswell's endorsement may have been prompted by a video McConnell's campaign launched earlier this month that questioned Bevin's conservative bona fides and noted Bevin supported her, as a Democrat, in a local election.

"According to McConnell, Kentuckians should only support candidates and ideas based on labels — not based on beliefs. According to McConnell, if the Republican establishment proposes an idea, he supports it, even if the policy is harmful for Kentucky and for the future of our great nation," she writes.

She adds that she was "proud" to have been "attacked" in the video. 

Bevin's campaign has ties to the Louisville Tea Party. His spokeswoman, Sarah Durand, previously served as president of the group but stepped down in July, prior to Bevin launching his bid.

Though Bevin continues to gain endorsements, his battle remains uphill. 

McConnell amassed a nearly $10 million war chest at the end of the last quarter, and has used it to continuously hammer his opponents. He's also worked to shore up support within his right flank, nabbing the endorsement of Tea Party darling Sen. Rand PaulRandal (Rand) Howard PaulSenate Dems hold floor talk-a-thon against latest ObamaCare repeal bill Overnight Defense: Senate passes 0B defense bill | 3,000 US troops heading to Afghanistan | Two more Navy officials fired over ship collisions Lawmakers grapple with warrantless wiretapping program MORE (R-Ky.) and hiring Paul's former campaign manager.

He's also received the endorsement of a number of other local Tea Party leaders, and released internal polling last week that gave him a 47-point lead over the challenger.