The Senate is racing against a Friday deadline to pass legislation to reauthorize the Federal Aviation Administration at a moment of intense uncertainty and disruption in the air travel system, but a host of policy disputes and unrelated issues are threatening to prolong the debate.
As one of the few remaining bills considered a must-pass item this year, the F.A.A. package has become a magnet for dozens of amendments and policy riders that lawmakers are fighting for a vote on, which has slowed its progress in the Senate. Regional interests have also scrambled the usual political alliances among lawmakers, making quick action trickier.
“All of us need to work constructively and with urgency to finish the job on F.A.A.,” Senator Chuck Schumer of New York, the majority leader, said on the Senate floor on Wednesday. “Nobody, absolutely nobody, should want us to slip past the deadline. That would needlessly increase risks for so many travelers and so many federal workers.”
The bill, which would reauthorize the agency for the next five years, would provide more than $105 billion to the F.A.A. and another $738 million to the National Transportation Safety Board for airport modernization, technology programs and safety. It also would bolster the hiring and training of air traffic controllers, codify airlines’ refund obligations to passengers and strengthen protections for passengers with disabilities.
The legislation is a bipartisan compromise negotiated over months by the Senate and House committees with jurisdiction over the F.A.A., after Congress authorized several short-term extensions of the agency when lawmakers failed to meet earlier deadlines. The House passed its version of the bill almost a year ago in a lopsided vote of 351 to 69.
“To get F.A.A. done, we need haste and a common desire to get to yes,” Mr. Schumer said on Wednesday. “Any member who insists on extraneous change will only increase the likelihood that we miss the deadline.”
With the legislation threatening to stall, the House on Wednesday approved a one-week extension before leaving Washington for the weekend. But it was not clear whether the Senate would be able to follow suit before the deadline, and leaders continued to push to move the longer-term overhaul.
The debate comes at a time of acute uncertainty about the aviation system, which has had a recent spate of concerning episodes such as dangerous near collisions on runways, plane malfunctions and thousands of flight delays and cancellations.
Senate leaders scheduled a key test vote for early Thursday afternoon, which will determine how quickly the bill can move forward.
Senator Ted Cruz of Texas, the top Republican on the Commerce Committee, said that the Senate had a “very good prospect of passing the bill” by Friday and that he expected “a strong bipartisan vote at the end of the day.”
“That’s what I’d like to see happen,” he said. “This is a bill that incorporates hundreds of member priorities from both sides of the aisle, makes real strides forward in terms of enhancing safety, in terms of investing in air traffic controllers to reduce delays.”
Senators maintain leverage as the clock ticks in a body that requires 60 votes to break a filibuster. They have filed dozens of amendments to the bill that they want Senate leaders to put up for a vote. Some proposals relate to the aviation system, while others are wholly separate pieces of legislation that proponents want to tack onto the F.A.A. bill to increase their chances of passage.
One of the most intense regional fights has been over a provision in the bill that would add five round-trip flights out of Ronald Reagan National Airport outside Washington, D.C. Proponents, which include Delta Air Lines, have said they want to expand access to the nation’s capital and increase competition.
But the proposal has incensed lawmakers representing the area, who have argued that the airport maintains the busiest runway in the country and cannot support additional flights. Senators Tim Kaine and Mark Warner of Virginia and Benjamin L. Cardin and Chris Van Hollen of Maryland, all Democrats, filed an amendment to strike the new flights. If they do not receive a vote on their proposal, Mr. Kaine and Mr. Warner threatened on Thursday to object to speedy passage of a one-week extension, which they said would allow leaders to run out the procedural clock on the broader package without allowing any amendment votes.
Another group of senators was pressing for a vote on their bipartisan proposal to halt the Transportation Security Administration’s expansion of facial recognition technology at airports and restrict it where it is in use.
Senators have also proposed adding a number of unrelated policy ideas.
Senator Josh Hawley, Republican of Missouri, demanded a vote on his bill that would expand eligibility for federal compensation for the group of people harmed by exposure to the nation’s nuclear weapons program. (The Senate passed the bill in March, but the House has not taken it up.) He also vowed to block quick approval of an extension if his measure did not receive a vote.
Mr. Cardin and Mr. Van Hollen wanted to add a bipartisan measure to allow the federal government to fully fund the replacement of the Francis Key Scott Bridge in Baltimore, which collapsed in late March.
Senators Richard J. Durbin of Illinois, the No. 2 Democrat, and Roger Marshall, Republican of Kansas, wanted to attach their legislation related to credit card competition.
And Senators Marsha Blackburn, Republican of Tennessee, and Richard Blumenthal, Democrat of Connecticut, were seeking to attach the Kids Online Safety Act, which would require social media networks to take “reasonable measures” to prevent harm to minors on their sites.
Senate leaders pointed to an overwhelming vote last week, 81-10, to begin consideration of the legislation as a sign of momentum and consensus around the measure. But they were still working on Thursday to secure an agreement to speed up the process, and the path to approving the short-term extension was not clear.
Senator John Thune of South Dakota, the No. 2 Republican, said on Wednesday that it seemed “increasingly unlikely” that an agreement could be reached, but that “there’s always hope.”
“Everybody’s got holds on this right now,” he said. “Whether or not they get fully exercised remains to be seen.”
Any major changes the Senate makes to the measure would jam the House, where leaders have urged their colleagues across the Capitol to keep out unrelated provisions.
The bill is a “carefully negotiated package, and support for the package could be compromised if the Senate starts unraveling key components of the agreement or adding completely unrelated legislation to the package,” said Justin Harclerode, a spokesman for Republicans on the House Transportation Committee. He added that policy riders could “complicate its passage in the House.”
Air travel industry players have urged quick passage of the bill to address a range of critical issues in the system and to provide the F.A.A. with long-term operating certainty.
“A4A supports the swift passage of the agreed-upon bipartisan, bicameral language that was released Sunday night after months of thoughtful negotiations,” Airlines for America, a trade group, said in a statement. “Extraneous, nongermane amendments threaten this must-pass bill amid a looming May 10 deadline.”
“We urge Congress to pass the F.A.A. reauthorization agreement without delay,” Sara Nelson, the president of the Association of Flight Attendants-C.W.A., A.F.L.-C.I.O., said in a statement. “This agreement will stabilize the F.A.A. and provide it with the resources necessary to ensure America’s aviation system remains the gold standard for safety, security and connectivity.”
