Sen. Rand Paul has single-handedly stopped the extension of three key provisions of the Patriot Act until after they expire at midnight Thursday. Unless he folds.

Kentucky Sen. Rand Paul speaks during a Tax Day protest April 15 in Bowling Green, Ky. (AP Photo/Daily News, Joe Imel)

The Senate voted to end debate on the measure, but Sen. Paul, a Kentucky Republican, is insisting the Senate debate the measure for a full 30 hours, which would extend beyond the midnight expiration. Mr. Paul’s tactic is procedural: By not agreeing to a request for unanimous consent to yield back debate time, he can insist the debate continues until 7a.m. Friday, past the midnight expiration of the provisions. Mr. Paul, a libertarian who opposes the Patriot Act, could change course and allow a vote before the provisions expire.

Senior lawmakers of both parties have urged the passage of the expiring provisions before the deadline, as have top figures in the U.S. intelligence community. The Director of National Intelligence James R. Clapper said in a letter to Senate leaders there could be serious repercussions for law enforcement’s ability to continue its surveillance efforts if the measures expire.

Senate Majority Leader Mitch McConnell, Mr. Paul’s fellow Kentucky Republican, also expressed dismay at the delay in a Senate floor speech Thursday morning, saying that it is “absolutely imperative” that the Patriot Act provisions are renewed. “Nothing in this extension has ever been found to be unconstitutional,” he said. “And most of these authorities haven’t even been challenged in court — ever.”…