Citing Supreme Court nominee Brett Kavanaugh's record on privacy issues, Sen. Rand Paul (R–Ky.) said Sunday that he has yet to decide if he'll vote to confirm the judge.

"I'm concerned about Kavanaugh," Paul said on Fox & Friends, alluding to the judge's views on the Fourth Amendment, which protects American citizens from "unreasonable searches and seizures." Paul explained that since President Donald Trump "did such a great job" with his first Supreme Court pick, Neil Gorsuch, he is keeping an "open mind" regarding Kavanaugh. But the Kentucky Republican is "worried" and "perhaps disappointed" that Kavanaugh may "cancel out Gorsuch's vote on the Fourth Amendment."

Paul referenced a 2015 ruling from the U.S. Court of Appeals for the D.C. Circuit that affirmed the National Security Agency's right to collect telephone metadata without a warrant. In his concurring opinion, Kavanaugh wrote that "the Government's metadata collection program is entirely consistent with the Fourth Amendment" and that "critical national security need outweighs the impact on privacy."

"I disagree completely," Paul said. "And I think if we give up our liberty for security, we may end up with what Franklin said, and that's neither—neither liberty nor security."

Paul said he's "willing to meet" with the judge to see how he would rule on other issues. "There are 10 rights…10 amendments listed in the Bill of Rights, and so the Fourth Amendment's one of them," Paul said. "So we're already down one, let's see how he does on the other nine."

Paul is not the only libertarian-leaning lawmaker to express concern over Kavanaugh's record on the Fourth Amendment. Minutes after Trump announced Kavanaugh's nomination, Rep. Justin Amash (R­–Mich.) called the judge a "Disappointing pick," adding that "We can't afford a rubber stamp for the executive branch."

But Paul's view is particularly important given the GOP's slim 51–49 majority in the Senate. If every Democrat votes against Kavanaugh, Republicans can only afford one defection. And if Sen. John McCain (R–Ariz.), who's being treated for brain cancer in Arizona, can't make it to D.C. for the vote, Republicans might need their entire caucus, including Paul, to support him.