House Transportation Committee Chairman John L. Mica says he is optimistic that Congress will break a stalemate over critical aviation funding before the current spending plan expires at year’s end.

Mica’s comment came after he met this week with a key Senate counterpart, John D. Rockefeller IV (D-W.Va.), to seek a compromise on aviation funding bills that passed the House and Senate earlier this year.

The meeting came Tuesday, a day after Rockefeller told an aviation industry gathering that prospects for agreement on a long-term funding bill seemed grim.

“I’m optimistic,” Mica said Wednesday. “We directed staff to try to resolve any of the pending issues and what can’t be decided [by them], we’ll meet and try to come to agreement.”

Long-term funding for the Federal Aviation Administration has proved to be as problematic and contentious as any issue on Capitol Hill in recent years, though it has played largely in the background to other high-profile partisan battles.

A long-term aviation spending plan is considered crucial to advancing a $42 billion program that will revolutionize the nation’s air traffic management system, keeping the U.S. industry competitive with its foreign counterparts and preparing for a projected huge increase in air travel in the next four decades.

Without confidence that Congress has committed to pay for the program, which has a long-term rollout, airlines have been reluctant to install equipment that will cost them up to $10 billion.

Despite bipartisan agreement on the need for the system, known as NextGen, Congress has been deadlocked on a spending plan, approving 22 extensions of current FAA funding since the last major spending authorization expired in 2007.

The holdup, which has endured since the days when Democrats had control of both houses, is largely over issues that are without a strong partisan taint. Only one — Republican desire to overturn a labor ruling that would make it easier for unions to organize Delta Air Lines — is rooted in political philosophy.

The others are more parochial than political. One is over the number of commercial flights that should be allowed at Reagan National Airport, and where airlines given new slots there should be allowed to fly. Members of Congress who can’t catch direct flights home have been frustrated by current restrictions.

Another key issue is a program that provides per-passenger federal subsidies that encourage airlines to provide service to rural airports. The program has been denounced as wasteful by Mica and others, mostly Republicans, who want to reduce or eliminate it.

The bill approved by the Senate would limit the program, capping subsidies at $1,000 per passenger and eliminating subsidies for airports within 90 miles of a major airport.

Rockefeller feels particularly aggrieved because it would eliminate subsidies to Morgantown in his home state, where the University of West Virginia is located.

One of the House staff members who will be party to the talks aimed at resolving the impasse was unsure whether the program — known as Essential Air Services — was still an issue.

“I don’t know whether it’s going to come up again or not,” the staff member said. “In our opinion the reform is done, but I don’t think that Senator Rockefeller is of the same opinion.”

Rockefeller on Monday told the Aero Club of Washington that “there’s no movement and no give. Once again we are stalled.” He predicted that when he met with Mica and two other key members the following day, “We will have almost nothing to say to each other.”

A day after that meeting, however, Mica said he thought the remaining issues could be resolved.

“I don’t what to say,” he responded when asked what issues remained. “They’re all things that are contingent. There’s a half a dozen.”