And it sounds like he's serious this time. If so, he's basically kissing his presidential ambitions goodbye much earlier than expected.

via Politico

Rand Paul plans to force the expiration of the PATRIOT Act Sunday by refusing to allow Senate Majority Leader Mitch McConnell to expedite debate on a key surveillance bill.

In a statement to POLITICO Saturday, Paul warned that he would not consent to any efforts to pass either an extension of current law or the USA Freedom Act, a reform bill passed overwhelmingly by the House earlier this month.

“So tomorrow, I will force the expiration of the NSA illegal spy program,” Paul said.
Because of the nature of the Senate rules, Paul can force the expiration of the PATRIOT Act, which he has vowed on the campaign trail to repeal as president because he contends it invades Americans’ privacy rights.

Paul's complete statement is at Politico.