The House has voted to back an amendment to limit the NSA's surveillance on Americans.
The amendment was adopted by what even supporters say was a surprisingly wide margin -- 293 to 123.
The legislation would require the NSA to obtain a warrant to search government databases for information on US citizens.
It would also prohibit surveillance "backdoor" gadgets on commercial tech products.
The amendment is attached to a defense bill, which is expected to have a final vote today.
If approved, the legislation would still need to pass in the Senate.