The FAA moved one step closer to a partial shutdown Thursday as lawmakers continued their disagreement over extending the FAA reauthorization bill.

Transportation Secretary Ray LaHood told reporters that without a bill by Friday night, government would furlough 4,000 employees in 35 states, including those working to engineer and implement the Next Generation air traffic control system, he adds.

“Without swift action from Congress, $2.5 billion for airport projects around the country” will be stalled, LaHood told reporters Thursday. “If we are not able to fund these projects, these people working on these projects will have to leave the job site on Saturday.”

On Thursday, the House passed the 21st extension to the FAA reauthorization bill, which includes a provision capping subsidies for the Essential Air Service (EAS) program at $1,000 per passenger. The change would effectively knock out three airports, including one in Ely, Nev., home state of Senate Majority Leader Harry Reid (D).

The Senate is refusing to accept the House extension, and Thursday, senators floated their own extension, one that mirrors the 20th and previous versions of the bill. And the administration wants the policy riders out as well.

“We have now reached the breaking point with unacceptable provisions in the House extension,” LaHood said.

And while FAA employees wait to see whether they’ll be working next week, lawmakers continue to trade barbs.

Rep. John Mica (R-Fla.), chairman of the House Transportation Committee, is using the Senate’s refusal to adopt the new EAS provision as a bludgeon, hammering senators for refusing to cut spending.

“The second provision sets a reasonable subsidy cap of $1,000 per passenger and eliminates three small airports from the program,” Mica said Thursday. “Shutting down FAA programs to protect these three highly subsidized airports would make absolutely no sense.”

And Sen. Jay Rockefeller (D-W.Va.), chairman of the Senate Commerce Committee, isn’t backing down, growling at his House counterpart not to “play games.”

From their actions and statements, the extension is designed to force the Senate’s hand on the provision to change the rules for National Mediation Board elections that the president has threatened to veto, Rockefeller said Thursday in a speech on the Senate floor.

“If the House continues its attempt to hold the Senate hostage … it will result in a partial shutdown” of the FAA, he added.

Rep. Johnny Isakson (D-Ga.), followed Rockefeller on the floor, saying that he has acted as a mediator between Mica and Rockefeller, particularly on the issue.

About one month ago, Isakson said he delivered a list of recommendations by the House that were rejected by the Senate majority leader. The House tried again, trying to make NMB decisions subject to judicial review. “As it turns out, that was an unsatisfactory offer,” Isakson said. “From my standpoint, I agree with the chairman that we need a reauthorization. But I also think we need a balanced view.”