According to one of the tea party's leading voices, Senate Minority Leader Mitch McConnell (R), who is being challenged by conservative Matt Bevin in Kentucky's Senate GOP primary, is not an "Arlen Specter" Republican.

"It's not like we're talking about Arlen Specter here," said Sen. Rand Paul (R-Ky.), in an interview with The Washington Post. "Senator McConnell has a longstanding conservative record and for an opponent to beat him, they'll have to prove somehow that he's not a conservative."

Specter, the late Pennsylvania senator who left the GOP for the Democratic Party in 2009, was a villain-like figure to many on the right, due to his moderate positions and frequent quarrels with conservatives.

Paul's comments come as several conservative advocacy groups, such as the Senate Conservatives Fund and the Madison Group, are supporting Bevin with a flurry of donations and ads, both online and on radio.

In one recently released spot, Bevin slammed McConnell for his support for a procedural vote on a measure to extend the federal government's borrowing authority. McConnell was spurred to back that vote, in spite of his earlier opposition, after Sen. Ted Cruz (R-Texas) demanded a 60-vote threshold for "cloture" on the legislation, which ends debate.

Paul, however, said McConnell's vote doesn't mean conservatives should rally behind Bevin. "Sometimes people don't always agree on tactics or deals, and I haven't always agreed with Senator McConnell," he said. "But I was of mixed feelings whether [Cruz's effort] was worthwhile, if we weren't going to actually add anything to it, if it was just self-inflicted punishment."

Paul and McConnell have seen their alliance grow over the past few years. When Paul ran for Senate in 2010, McConnell backed his Republican primary foe, Trey Grayson, and feelings between their camps were tense. Last week, they appeared together at a fundraiser in Louisville, and Jesse Benton, Paul's longtime strategist, is managing McConnell's campaign.

"I'm not offended by having a primary," McConnell said on Friday, according to CNN. "I don't have any sense of entitlement. I don't own this seat. I have to earn it, and I'll earn it in both the primary and the general."

If McConnell wins the May Republican primary, he will face Democrat Alison Lundergan Grimes in the general election. Grimes, Kentucky's 35-year-old Secretary of State, is an ally of the Clinton family, and former president Bill Clinton stumped for her earlier this week.

When asked whether Grimes, who is one of the state's youngest elected officials, is ready to serve in the Senate, Paul said Grimes's biggest liability isn't her age or experience, but her ties to President Obama.

"She's already sensing that Kentuckians don't like the president's policies," he said. "What is she going to do? Run as someone who's opposed to all of his policies? She's trying to back away from his war on coal; she's trying to back away from Obamacare."

Related: Bill Clinton in the Bluegrass State