A pair of House Democrats on Wednesday urged lawmakers to support an amendment by Rep. Justin Amash Justin AmashOn The Trail: How Nancy Pelosi could improbably become president History is on Edward Snowden's side: Now it's time to give him a full pardon Trump says he's considering Snowden pardon MORE (R-Mich.) that would restrict a National Security Agency surveillance program that collects the phone data of people in the United States.



In a "Dear Colleague" letter sent to House members, Reps. John Conyers (D-Mich.) and Zoe Lofgren (D-Calif.) said the amendment would make an "important improvement" to the NSA's data collection program by preventing the spy agency from using its funds to collect the phone records of people who are not under investigation.



Amash's amendment to the 2014 defense spending bill is expected to be put to a vote Wednesday evening. Conyers is the lead Democratic co-sponsor of the amendment.

The White House and congressional leaders on the Intelligence Committees have been working to rally opposition to the amendment, saying it would undermine a vital counterterrorism program that has thwarted attacks against the country.



The vote will signal House members' temperature towards supporting the NSA surveillance programs that came to light last month.



The NSA uses its authority under section 215 of the Patriot Act to operate the phone data collection program, which collects the call records of people in the U.S. Conyers and Lofgren argue that the spy agency has been using this authority to "allow the bulk collection of information about all Americans."



Amash's amendment would limit the NSA's authority to sweep up U.S. citizens' phone data, the two lawmakers argued.



"This amendment would not prohibit the government from spying on terrorists under Section 215, or from collecting information in bulk about Americans under other legal provisions," the lawmakers write. "However the amendment would prevent the bulk collection of sensitive information on innocent Americans under Section 215—an important improvement."