UPDATE: The headline of this article was changed on Thursday, following news that Senate Minority Leader Mitch McConnell (R-Ky.) filed cloture on both the USA Freedom Act and a short-term “clean” reauthorization of expiring Patriot Act surveillance authorities (despite Sen. Paul’s “filibuster”). That sets up a Saturday vote on both measures. Original story continues below…

With the expiration of key surveillance authorities imminent, Sen. Rand Paul (R-Ky.) burned up crucial legislative time on Wednesday after he promised to speak from the floor of the Senate “until he can no longer speak” against National Security Agency spying programs revealed by former NSA contractor Edward Snowden.

Although the speech–ongoing, as of publication–isn’t technically a “filibuster,” as Sen. Paul’s office described it, the long-winded tirade may choke the last bit of life out of a gambit by his fellow Kentucky Senator, Majority Leader Mitch McConnell (R-Ky.), to reauthorize expiring USA Patriot Act mandates without any of the minor reforms recently approved by the House.

“I will not let the Patriot Act, the most un-patriotic of acts, go unchallenged,” Paul said just before 1:30 p.m. EST, at the onset of his stemwinder.

The junior Senator from Kentucky relied on newspaper reports, research by prominent privacy advocacy groups, and public statements made by Snowden and fellow former NSA insider Bill Binney to detail the agency’s bulk collection activities, and to recall how unauthorized disclosures exposed the guts of internet surveillance programs like PRISM, UPSTREAM, and MUSCULAR.

“The collection of records that is going on is beyond your imagination. And we need to know about it. It’s time for a national debate,” Paul said.

Last week, the GOP presidential hopeful promised to filibuster an extension of the USA Patriot Act. At the time, Sen. McConnell and Senate Intelligence Committee chair Richard Burr (R-N.C.) had been pushing for such a move–a so-called “clean” reauthorization of Section 215 of the post-9/11 national security law, which the government has partially relied upon to conduct programs discussed by Paul on Wednesday afternoon. McConnell and Burr’s plans have, since, largely fallen apart due to time constraints and political realities on the south side of the dome–lower chamber supporters of the aforementioned reform bill, the USA Freedom Act, notified McConnell that they would oppose any boilerplate extension of Section 215.

Increasing the pressure on Senate leaders is the fact that the House is slated to recess Thursday afternoon. If Congress fails to act on surveillance authorities by then, the key War on Terror era statute will likely expire–a move that could have significant consequences, even if influential lawmakers labor quickly to restore the mandate. The NSA on Wednesday circulated a memo to congressional offices, warning lawmakers that unless a deal is struck to extend PATRIOT Act authorities before May 22, the agency “will need to begin taking steps to wind down the bulk-telephone-metadata program in anticipation of a possible sunset in order to ensure that it does not engage in any unauthorized collection or use of the metadata.”

Seemingly accepting the political reality he was facing earlier this week, Sen. McConnell scheduled an imminent vote on the USA Freedom Act. Although the bill would, much to hawkish lawmakers’ dismay, reform the NSA’s call records collection program, it would also extend Section 215 surveillance authorities into 2019.

A critic of the bill, Paul’s speech could be seen as a protest against a major reform he sees as insufficient. The senator voted down the first incarnation of the Freedom Act last December, and said on Wednesday that he doesn’t “agree completely—or really at all—with the USA Freedom Act.”

But the move could also be seen as a stunt to boost his presidential campaign, with a straight extension proposed by McConnell highly unlikely to pass, and Section 215 expiration unlikely in a town where security state feamongering is valuable currency. Paul has, after all, made NSA reform a cornerstone of his platform.

Regardless, McConnell was effectively prevented from taking advantage of a slow day in the Senate to slip a clean Patriot Act reauthorization through the cracks—a concern that Sen. Ron Wyden (D-Ore.) confessed to having when he joined in on Paul’s marathon oration.

“A number of us—myself specifically—have been concerned that the Majority Leader and other supporters of ‘business as usual’ on bulk collection of all of these phone records would somehow try to take advantage of our current discussion and try to, in effect, sneak through a motion to extend section 215 of the USA Patriot Act,” Wyden said, giving Paul a breather.

“As long as the Senator from Kentucky has the floor that cannot happen,” Wyden added.

In order to actually disrupt McConnell’s planned proceedings, Paul will have to speak for nearly 24 hours–until the time when the Senate is scheduled to hold a vote on trade legislation.

During a previous “filibuster” in March 2013, Sen. Paul spoke for nearly 13 hours against the confirmation of John Brennan as CIA Director.