"Tomorrow, I will force the expiration of the NSA illegal spy program," Paul said.
The senator added that he would start the debate on how the United States should fight terrorism without giving up civilian liberties, not allowing Senate Majority Leader Republican Mitch McConnell to expedite it.
"I do not do this to obstruct. I do it to build something better, more effective, more lasting, and more cognizant of who we are as Americans," Paul concluded.
The senator had already filibustered the renewal of the Patriot Act legislation last week, when he spoke on the Senate floor for ten hours, delaying all legislative business.
Before the May 25, 2015 Memorial Day recess, both bills had already failed a vote in Senate.
In early May, a US court of appeals ruled that government bulk collection of personal data, justified under the Patriot Act, was a violation of the US Constitution.