The Senate Commerce, Science and Transportation Committee approved a bipartisan bill to reauthorize the Federal Aviation Administration in June of last year. But the measure’s proponents have struggled ever since to get it to the floor, even as another deadline approaches at the end of this month.

Congress could be headed toward its sixth straight extension of FAA authorization if both chambers can’t pass a yet-unfinished conference bill before Sept. 30. House leaders on the issue, who steered easy passage of their measure earlier this year, have blamed the other chamber, which hasn’t passed its own bill.

Senate leaders have been unwilling to spend significant floor time on the bill, so Commerce Chairman John Thune of South Dakota and ranking Democrat Bill Nelson of Florida have pushed for a time agreement that would limit debate and the number of amendments that may be considered. But such an agreement requires all senators to sign off, and a handful of issues have blocked unanimity.

An amendment related to trucking labor laws emerged recently as the most contentious issue, but the committee has also had to deal with attempts to include tax policy and an autonomous vehicles bill.

Thune and Nelson have tried to partially circumvent the Senate floor, hoping to iron out differences between theirs and the House-passed bill. But the absence of a Senate-passed measure has complicated those negotiations.

Oregon Rep. Peter A. DeFazio, the ranking Democrat on the House Transportation and Infrastructure Committee and a co-sponsor of the House measure, said his Senate counterparts are trying to negotiate 90 floor amendments, which have not passed, to the committee-approved bill.

Asked last week what particular issues were holding up “pre-conference” talks, DeFazio answered: “The United States Senate.”

“They have an imaginary bill that they couldn’t take up and couldn’t pass on the floor, with 90 imaginary amendments that they say could’ve passed and they are insisting on all of that. And we have differences even over the base bill. So we’ll see. We’re talking to them,” he added.

Members are loath to admit it, but the odds of getting a compromise authorization bill to the president’s desk before the Sept. 30 deadline are short.

“Not gonna do an extension,” House Transportation Chairman Bill Shuster said. “Thune and I are sticking tight to it.”

The Pennsylvania Republican said most members of both parties on both sides of the Capitol wanted to get an FAA bill done. But when asked how that could be accomplished given the constraints on the Senate’s floor schedule — prioritizing votes on appropriations bills and confirmations, including the Supreme Court — he couldn’t say.

“I don’t know anything about floor time over there,” he said. “I don’t know how that place works.”

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Seeking urgency

Thune said the cycle of extensions on FAA authorization has hurt its importance in the eyes of a lot of senators.

“It doesn’t have the sense of urgency around it because we’ve done short-term extensions and can do short-term extensions,” he said. “For a lot of people, at least, it’s not like a life-and-death issue, so it’s just hard to keep it front and center in terms of the agenda.”

If House and Senate negotiators are unable to reach a deal by Sept. 30, Thune said he would pursue a short-term extension that would go no later than the end of 2018.

Even with a chance to take control of the chamber next year, House Democrats are also hoping to enact the bill as soon as possible.

After Shuster dropped his controversial bid to spin off air traffic control operations to a private nonprofit, House members wrote a consensus bill that included what Democrats wanted without anything they couldn’t stomach.

“I don’t think the bill could be demonstrably better,” said Washington’s Rick Larsen, the ranking Democrat on the House Transportation Aviation Subcommittee, when asked if Democrats would like to write their own bill. “There are some things we could take out, but would it be much different? Do we need five more FAA hearings to change 2 percent of the bill? I don’t think so.”

Missouri Rep. Sam Graves, who would be a candidate to lead the committee if Republicans keep the House, also said he’d prefer lawmakers pass a bill this year. If he had the gavel after Congress passed an extension into January, he said he’d just pick up the consensus bill rather than starting the process over.

Fallout

Although it’s been difficult to get rank-and-file members to focus on the issue, those who wrote the bills say there are dire consequences of inaction.

Rep. Frank A. LoBiondo, a New Jersey Republican who chairs the Aviation Subcommittee, said the cycle of extensions “kills me.” Every time a deadline approaches, the agency’s highly trained workforce has to stop its work, then restart again once an extension or reauthorization is enacted. The process interrupted important work and created unneeded cost, he said.

“Contrary to what a lot of people think here, that it doesn’t make a lot of difference, of the 3,500-plus people who work there, most of them are engineers and Ph.D.s who have to stop what they’re doing on critical programs to the nation and prepare for a shutdown, which is insanity and nonsensical,” he said.

Members of Congress and outside groups also say not enacting a full authorization bill would hurt industries related to aviation, especially manufacturers of drones and planes and associated parts.

For drones, in particular, the growing industry needs Congress to act to allow the technology to be used in new ways. A 2012 FAA law barred the FAA from regulating certain uses of drones. The law’s prohibition on new regulations means the FAA cannot write a rule to allow flights over people, for example, which makes delivery by drones impractical.

The agency also cannot establish a user identification system, which then restricts the ability to use the national airspace.

The House and Senate versions of the bill include provisions that would alter the restriction on the FAA’s rule-making.

“From the drone perspective, the biggest concern with an extension and not anything substantive on policy is there are a lot of things that are waiting on this bill,” said Jamie Boone, the senior director of government affairs at the Consumer Technology Association. “Without a bill, we’re still in limbo.”

Another long-sought policy area at play is an overhaul of the rules to certify aircraft and parts for safety. Larsen said the global competitiveness of Boeing and other aerospace manufacturers in his state is at stake if Congress cannot enact the changes to aircraft certification that he and others have sought for years.

Larsen and DeFazio have made changes to certification a top issues on FAA bills going to back to 2015, when DeFazio took over as the top Democrat on House Transportation.

DeFazio said previous extensions were the result of Shuster’s focus on “privatization” of air traffic control, though the Oregon Democrat did not name the chairman. Shuster finally accepted defeat on that proposal in February when it became clear not enough Republican votes would overcome the near-universal opposition from Democrats.

“We’ve done too many extensions,” DeFazio said. “We needed certification reform three years ago. We wasted three years on privatization. … It’s time to get the damn bill done.”