The U.S. Senate is poised to vote on a bill that would expand the FBI’s secret surveillance powers, including warrantless collection of browsing history, Reuters reports.

Lawmakers will vote on the amendment, sponsored by Sens. John McCain (R-Ariz.) and John Cornyn (R-Texas), no later than Wednesday.

If approved, the bill would expand the FBI’s authority to use the so-called National Security Letters (NSL) to obtain Electronic Communication Transaction Records (ECTR) such as email time stamps, senders, and recipients, as well as browsing metadata such as history and location—all without a warrant.

The amendment, which McConnell attached to a criminal justice appropriations bill, has received widespread criticism from civil liberties groups.

Digital rights organization Electronic Frontier Foundation (EFF) previously referred to the NSLs as “one of the most frightening and invasive” government surveillance powers that were expanded under the U.S. Patriot Act, and noted that the FBI is guilty of “systemic abuse of this power.”

NSL recipients are also subject to a gag order that prohibits them from ever revealing the existence of the letters to anyone, from their coworkers to the public at large.

Fight for the Future launched a campaign calling on senators to vote it down, stating, “The information the FBI wants is too sensitive to remove oversight.”