WASHINGTON — House leaders have agreed to permit a vote on tightening limits on when the F.B.I. may collect Americans’ internet browsing and search records during national security investigations, after negotiations over Memorial Day weekend between two California Democrats, Representatives Zoe Lofgren and Adam B. Schiff.
A vote on the proposal — an amendment to a peripatetic bill related to the Foreign Intelligence Surveillance Act, or FISA, that both the House and Senate have passed in different forms — is likely to come this week. If it passes, the bill would return to the Senate, extending its long-running consideration.
But by Tuesday night, there were multiple signs of political turbulence that raised new doubts about the bill’s future.
The text of the compromise amendment was not yet public, but congressional aides said that the proposal essentially limits to Americans the protections of a Senate proposal that would categorically ban the F.B.I. from using a court order for business records to collect internet browsing and search records.
The House is preparing to vote this week on the overall bill, which centers on extending three partly expired tools the F.B.I. uses to hunt for spies and terrorists.
It has also become a vehicle for broader changes to surveillance matters, with lawmakers who have long championed civil liberties teaming up with allies of President Trump after an inspector general report uncovered myriad problems in FISA surveillance used in the Trump-Russia investigation. The result is a mix of overhauls and new restrictions — some related to the Russia case and some not.
Complicating matters, however, Mr. Trump abruptly urged Republicans late Tuesday on Twitter to vote against the FISA bill even though it contains changes in response to his complaints, including generally requiring the appointment of an outsider in the FISA court to argue against the government’s position if the surveillance would affect a political campaign.
“I hope all Republican House Members vote NO on FISA until such time as our Country is able to determine how and why the greatest political, criminal, and subversive scandal in USA history took place!” Mr. Trump wrote on Twitter.
The president has a history of erratic intervention in FISA legislation politics. In January 2018, when Congress was about to extend a different part of that law that permits warrantless surveillance of noncitizens abroad, he abruptly urged lawmakers to vote it down after watching a segment on Fox News — only to walk back his remarks hours later. It passed.
The House passed a version of the current bill in March. But this month, when the Senate took up the bill, senators approved a different amendment to it while narrowly rejecting another one about internet records, sponsored by Senators Ron Wyden, Democrat of Oregon, and Steve Daines, Republican of Montana.
A majority — 59 of the 100 senators — voted for the Wyden-Daines amendment, which would have banned the F.B.I. from gathering internet records using a type of FISA court order that permits collection of business records deemed relevant to a case. But it fell one short needed under Senate rules to attach it to the bill at that stage.
Because the Senate modified the bill, it returned to the House for another vote. Galvanized by the close vote, privacy advocates like Ms. Lofgren used the opportunity to push House leaders for permission for an up-or-down vote on the same idea.
Speaker Nancy Pelosi instructed Ms. Lofgren to negotiate with Mr. Schiff, the chairman of the House Intelligence Committee, to see whether they could arrive at compromise language that would narrow the Senate version. Over the holiday weekend, they agreed to limit the protection to Americans.
It was not clear, however, how far the new rule would go, were it to be enacted into law.
For one thing, the restriction would apply only to business records orders collected under a provision of law known as Section 215 of the USA Patriot Act, which allows the F.B.I. to collect such records deemed relevant to a terrorist investigation. (It is also one of the three provisions that have now partly lapsed, but would be revived and extended.)
But the government has sometimes used a different provision of FISA, the “pen register/trap and trace” section, to gather internet metadata. Orders to install a pen register device have the same low standard as orders requiring the production of business records.
Moreover, aides said the amendment would not explicitly lay out whether the proposed limit on using Section 215 business records orders would apply to situations where the F.B.I. does not know ahead of time whose data will be collected — like when it may want to gather the addresses of all visitors to a website or viewers of a video.
Ms. Lofgren declared that the language, should it become law, should be interpreted strictly as an “outright prohibition” on collecting Americans’ data — even if it was incidental.
For example, she said, the F.B.I. could not use a Section 215 order to get “a list of everyone who has visited a particular website, watched a particular video or made a particular search query” unless it could somehow guarantee that no Americans would be caught in the net.
But in his own statement, Mr. Schiff put forward a narrower emphasis. Stressing the continued need to investigate foreign threats, he described the compromise as banning the use of such orders “to seek to obtain” an American’s internet information.
That formulation left open the possibility of interpreting the potential new law as banning only deliberate attempts to collect an American’s data, leaving the F.B.I. free to ask for lists of all visitors to websites despite the risk that the list may turn out to incidentally include some Americans.
One traditional means by which courts interpret ambiguously written statutes is by looking at evidence of legislative intent — like statements by lawmakers explaining what they believed a bill would do before a vote — so such statements may in part be an attempt to create fodder to argue about what the compromise language means in future litigation.
Mr. Wyden, who initially issued a statement on Tuesday endorsing the compromise House language and echoing Ms. Lofgren’s claims about what he believed it would mean, said later Tuesday that in light of Mr. Schiff’s suggestion of a narrower understanding, he would no longer support the measure and wanted his original version.
“It is now clear that there is no agreement with the House Intelligence Committee to enact true protections for Americans’ rights against dragnet collection of online activity, which is why I must oppose this amendment, along with the underlying bill, and urge the House to vote on the original Wyden-Daines amendment,” Mr. Wyden said.