WASHINGTON (AP) — Legislation extending surveillance authorities the FBI sees as vital in fighting terrorism was thrown into doubt as President Donald Trump threatened a veto and Republican leaders and top liberal Democrats said they would oppose it.

House Democratic leaders abruptly adjourned without considering the bill, hours after saying there would be a vote Wednesday evening. In between, Trump said explicitly for the first time he would veto the measure. A similar version of the legislation had drawn bipartisan support just weeks ago.

"If the FISA Bill is passed tonight on the House floor, I will quickly VETO it," Trump tweeted, using the acronym for the Foreign Intelligence Surveillance Act. "Our Country has just suffered through the greatest political crime in its history. The massive abuse of FISA was a big part of it!"

Trump had suggested Tuesday he would oppose the measure, prompting Republicans who once backed the deal to follow Trump's lead and say Wednesday they would vote against it.

The leaders of the Congressional Progressive Caucus, which has about 70 Democratic House members, also said they'd oppose the legislation, saying it lacked curbs on online surveillance without warrants.

Combined with strong GOP opposition, the Democrats' defiance of House Speaker Nancy Pelosi, D-Calif., suggested there might be enough dissent to sink the bill. It was unclear if Democratic leaders would try again Thursday to hold a vote or if they'd skip a vote and try to negotiate with the Senate on a final compromise.

"We cannot in good conscience vote for legislation that violates Americans' fundamental right to privacy," said the progressive caucus' leaders, Reps. Pramila Jayapal, D-Wash., and Mark Pocan, D-Wis.

The legislation first passed the House in March with broad bipartisan support after Attorney General William Barr negotiated a deal with Republican and Democratic House leaders. But that consensus crumbled Wednesday after the Justice Department came out against the bill, which was amended by the Senate. The Justice Department's statement, by Assistant Attorney General Stephen Boyd, urged Trump to reject the bill.

Soon after, House Republican Leader Kevin McCarthy, R-Calif., said it was time to take a "pause" on the legislation.

The impasse raised the potential for the surveillance powers to remain expired indefinitely. The provisions, which lapsed in March, allow the FBI to get a court order for business records in national security investigations and conduct surveillance on subjects without establishing they're acting on behalf of an international terrorism organization. They also make it easier for investigators to continue eavesdropping on a subject who has switched cellphone providers to thwart detection.

Despite the sudden GOP switch, Democratic leaders said they'd move forward with a vote anyway, arguing very little had changed since 126 Republicans, including McCarthy, voted for it in March.

"Your flailing around to find a rationalization for your change of vote is sad," House Majority Leader Steny Hoyer, D-Md., told Republicans in a heated floor speech.

"The only thing that has changed," Hoyer said, "is that Donald Trump has said vote no."

With Republicans opposed, Pelosi needed to keep her caucus together to pass it. But losing the progressives — lawmakers who've long opposed surveillance laws — made that a lot harder. On the floor, she pleaded with her colleagues to support the legislation to protect national security and pass reforms to protect civil liberties that were included in the original compromise.

"If we don't have a bill, then our civil liberties are less protected," Pelosi said.

The only amendment adopted by the Senate, with 77 votes, was bipartisan language to allow more third-party oversight to protect people in some surveillance cases. The final bill passed the Senate with 80 votes.

The Justice Department's statement said that amended Senate version of the bill would "weaken national security tools while doing nothing to address the abuses" identified by the Justice Department inspector general in his report on the FBI investigation into ties between Russia and the 2016 Trump campaign.

Trump, still seething over the Russia investigation, implored all House Republicans in a Tuesday tweet to vote no "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!"

McCarthy said lawmakers passed the legislation with bipartisan majorities before and should try again to negotiate a compromise.

"If the Democrats bring this bill up they're just playing politics," McCarthy said. "And this is not something to play politics with."

The statements underscored the tortuous process Congress has faced in renewing the surveillance powers since an inspector general report that documented serious errors and mistakes in how the FBI used its authorities during the Russia investigation. Those problems included errors and omissions in applications the FBI submitted under the Foreign Intelligence Surveillance Act to monitor a former Trump campaign adviser.

Republicans have historically been hawkish on preserving surveillance powers in the name of national security. But Trump's GOP allies have joined him over the last year in demanding that any renewal of the FBI's powers be accompanied by significant new restrictions.

The powers are not directly related to the errors uncovered during the Russia investigation. But Republican lawmakers — and some Democratic civil liberties advocates — have seized on those problems in demanding reforms.

The Senate passed its version of the legislation this month. The chamber fell short by one vote of adding an amendment, sponsored by Democrat Ron Wyden of Oregon and Republican Steve Daines of Montana, that would prevent federal law enforcement from obtaining internet browsing information or search history without seeking a warrant.

House Intelligence Committee Chairman Adam Schiff, D-Calif., announced Tuesday that Democrats had agreed on a similar amendment that they would offer to the House bill. But that amendment faced opposition from the Justice Department and from Wyden, who said the House version would not "enact true protections for Americans' rights against dragnet collection of online activity."

Democrats later dropped the amendment and said they instead would hold the vote on the Senate version with no amendments offered.

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Associated Press writer Alan Fram contributed to this report.