The Senate on Monday night voted 74-8 to move forward with a bill that would extend provisions of the Patriot Act until June 1, 2015.
The procedural vote puts the legislation on track to pass the Senate Wednesday with a simple majority.
Leaders from both parties supported the bill and said it contains measures crucial to protecting the U.S. from terrorist attacks.
"We have to renew the Patriot Act," said Senate Majority Leader Harry Reid (D-Nev.) from the Senate floor. "It is not a perfect law but it plays an important part in keeping us safe."
"Our country faces a sophisticated, lethal threat from al Qaeda, associate groups and self radicalized terrorists," added Minority Leader Mitch McConnell (R-Ky.) in a statement. "The Patriot Act is one of the critical tools for keeping America safe."
A small but vocal group of senators opposed the bill, however, claiming it erodes the checks and balances of the Constitution and trades privacy for security.
"The Patriot Act takes away some of the protections provided by the Fourth Amendment," said Sen. Rand Paul (R-Ky.). "Do we really want to give up our liberties in exchange for more security?"
"Our constitutional freedoms are too valuable" to pass the extension, added Sen. Jon Tester (D-Mont.).
The Senate's version of the Patriot Act would extend the ability of U.S. intelligence authorities to conduct roving wiretaps, gain access to business records and survey "lone-wolf" operators, non-U.S. citizens not connected to organized terror groups but believed to be acting alone. Those authorities expire at the end of the week.
Now that the chances of the legislation's ultimate passage have been bolstered by achieving the 60-vote threshold required for cloture, senators both for and against the bill will try further shape the bill through the amendment process before the final vote later in the week.
Sens. Patrick Leahy (D-Vt.) and Paul, for example, will seek to include more government oversight of the act's authorities and sunsetting the use of national security letters (NSL) as a basis for justifying intelligence gathering.
The Senate adjourned at 7:04 p.m. on Monday and is set to to return at 10 a.m.
This article was updated at 7:05 p.m. on Monday.