Kentucky Sen. Rand Paul said Wednesday that he will hold John Brennan's nomination as CIA Director until he receives "sufficient answers" about the Obama administration's drone policy.

“I have asked Mr. Brennan if he believed that the President has the power to authorize lethal force, such as a drone strike, against a U.S. citizen on U.S. soil, and my question remains unanswered," Paul said in a statement. "I will not allow a vote on this nomination until Mr. Brennan openly responds to the questions and concerns my colleagues and I share."

Paul's threats are the latest Cabinet confirmation headache for the White House, coming on the heels of Republican opposition to Secretary of Defense nominee Chuck Hagel.

While Democrats almost certainly have the votes to overcome any nomination "holds," the recalcitrance to Obama's Cabinet replacements is virtually unprecedented in Senate history.

The libertarian-leaning Senator has sent two very extensive letters to Brennan, demanding answers to at least 30 questions about the Obama administration's drone program. In his statement, Paul said he will block Brennan's confirmation until those questions are "sufficiently answered."