Lawmakers agreed to postpone production of the F-22 fighter plane until April 2001 but refrained from eliminating the program outright as negotiators worked yesterday on the details of a compromise brokered by House and Senate leaders Wednesday night.

The tentative agreement, which would provide $1 billion in funding and would allow the purchase of up to six planes, marks a victory for House lawmakers who sought further testing of the sophisticated aircraft.

The compromise clears the way for passage of the nearly $270 billion defense spending bill. Negotiators will meet Monday to finalize the measure, which is headed for a floor vote early next week.

Both sides said they were satisfied with the agreement, which provides $723 million for research and development as well as testing and evaluation, along with $277 for advanced procurement. Lawmakers also will establish a reserve fund of $300 million to cover any liabilities the Air Force might incur as a result of terminating the program's contracts.

House appropriators shocked the Air Force in July when they voted to remove the $1.8 billion requested by the Air Force to buy the first six F-22s and instead put $1.2 billion toward research and development. But lawmakers said they were challenging continued funding of the plane to force a major debate in Congress over whether the United States can afford the F-22 in addition to two other new jet fighters in the works.

"We said from the start we needed more testing," said Rep. John P. Murtha (Pa.), the House Appropriations Committee's ranking Democrat, who joined the panel's chairman, Rep. Jerry Lewis (R-Calif.), in opposing the program. "That's where we're heading."

Georgia lawmakers, whose state manufactures the aircraft and who lobbied aggressively to preserve funding for the program, said they also approved of the compromise.

"We feel like that agreement represents a victory over the most significant threat to the future of the F-22 program," said Laura Cox, a spokeswoman for Sen. Paul Coverdell (R-Ga.). "The action taken on the House side was extremely irresponsible."

Pentagon officials described the proposal as a palatable outcome to a bad situation.

"It is important that the program is not shut down because then it can be impossible to restart," a senior Pentagon official said, adding that the Defense Department hopes that with further testing it will be able to win over the F-22's skeptics and move into full production without too much delay.

The Air Force has promoted the plane as essential to maintaining control of the skies against new generations of aircraft and surface-to-air missiles under development by Russia and the Europeans. The aircraft is intended to succeed the F-15 and lead to development of a less expensive, multi-service Joint Strike Fighter.

The F-22 uses stealth technology to evade radar and can "supercruise" at 1 1/2 times the speed of sound without fuel-guzzling afterburners. Its advanced cockpit displays would allow pilots to identify and attack enemy aircraft well beyond visual range.

But at an estimated $187 million per plane, the F-22 also would be the most expensive fighter ever produced. Its cost has more than doubled as a result of problems in developing its revolutionary airframe and advanced avionics.

Lewis and other critics of the program argued that the F-22 made sense when the United States faced a Soviet superpower capable of developing ever more sophisticated aircraft. But they said other problems have become more pressing in the past decade, including difficulties retaining Air Force pilots and shortages in reconnaissance, refueling and transport aircraft.

Staff writers Bradley Graham and Roberto Suro contributed to this report.