Majority Leader Harry Reid promised Senator Rand Paul 30 hours of debate, and now Paul is refusing to yield back his time. From the Wall Street Journal:

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. 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.

As I wrote earlier in the week, allowing the act to sunset won't jeopardize national security.