WASHINGTON — Two influential Democrat lawmakers warned on Thursday that they will not support boosting the number of Lockheed Martin-made F-35 joint strike fighters in the upcoming fiscal 2022 budget unless the program makes headway in addressing a laundry list of problems.

“If this program continues to fail to significantly control and reduce actual and projected sustainment costs, we may need to invest in other, more affordable programs and backfill an operational shortfall of potentially over 800 tactical fighters,” said Rep. Donald Norcross, D-N.J., who chairs the House Armed Services Committee’s tactical air and land subcommittee.

“Given the overall affordability concerns that exist within the program, I would not support any requests for additional aircraft beyond what is contained in this year’s president’s budget request,” he said during a hearing on the F-35.

Rep. John Garamendi, D-Calif., who leads HASC’s readiness subcommittee, doubled down on Norcross’s vow to fight adding extra F-35s to the FY22 budget.

“The program is over budget. It fails to deliver on promised capabilities. And its mission capability rates do not even begin to meet the service thresholds,” Garamendi said. “Industry’s solution to many of these problems is simply to ask the taxpayers to throw money at the problem. That will not happen. The easy days of the past are over.”

“Don’t expect more money,” he added. “Do not expect to have more planes purchased than authorized in the president’s budget. That’s not going to happen.”

During the joint hearing of HASC’s readiness and tactical air subcommittees, lawmakers expressed alarm about a long list of issues, including an ongoing shortage of the jet’s Pratt & Whitney F135 engine and maintenance costs that — if left at current levels — service officials have said would be untenable.

They also indicated concerns about the “Tech Refresh 3” effort that upgrades the F-35′s computing systems, which Norcross said was five months behind schedule and will likely be nearly $450 million over its planned budget, as well as anticipated delays on the Block 4 modernization program that improves software and adds new weaponry to the aircraft.

Norcross and Garamendi’s comments could represent a shift among lawmakers, who have since 2015 persistently added F-35s to the defense spending bill above and beyond what the Air Force, Navy and Marine Corps asked for in their budget requests.

In FY21, for instance, the Defense Department requested 79 joint strike fighters. Ultimately, congressional appropriators boosted funding for the program by $1.6 billion in order to buy an additional 17 jets: 12 F-35A conventional-takeoff-and-landing models for the Air Force, and seven F-35C carrier variants for the Navy and Marine Corps.

The Defense Department purchased 98 F-35s in FY20, in part due to lawmakers adding a total of 20 jets to the omnibus spending bill.

“The tactical air and land subcommittee has been supportive of this program in the past,” Norcross said. “But as we’ve said many times, we don’t have unlimited resources as we chase this elusive affordability of the program.”

Garamendi added that the F-35s added to the budget have only compounded the sustainment challenges faced by the military.

Although Democrats were more vocal about their concerns, GOP lawmakers also acknowledged that the program could face severe cuts unless performance improved.

“If our industry stakeholders don’t succeed in quickly driving down the sustainment cost of the F 35. I fear critics of the program will be dealt a stronger hand in their calls to gut the program,” said Colorado Rep. Doug Lamborn, the top Republican on the readiness subcommittee.

Missouri Rep. Vicky Hartzler, the ranking Republican on HASC’s tactical airpower subcommittee, stated that the F-35 program is making some progress, but added that she shared her colleagues’ concerns about capability delays, affordability issues and readiness problems.

Norcross and Garamendi could find support for restricting the number of F-35s purchased per year from HASC Chairman Adam Smith, D-Wash., who called the program a “rathole” in March. During a Thursday morning event hosted by the American Enterprise Institute, Smith said he intends to keep the pressure on the F-35 joint program office and Lockheed Martin.

“I know how important the F-35 is, I do. And for all those people out there trying to educate me on it, I have been to the classified briefings. I know what the Chinese have as well as anybody,” he said. “But at $38,000 an hour to fly with an availability rate sub 50 percent, with an engine that is apparently going to become very difficult to fix past about 2030 so that even fewer of our planes are available, I think we can do better.”

Although the Air Force, Navy and Marine Corps have repeatedly placed additional F-35s on their unfunded priorities lists — which essentially functions as a wish list of items the services would like to buy if their budgets were larger — there are signs that at least the Air Force could try to roll back this practice.

Lt. Gen Clint Hinote, the Air Force’s deputy chief of staff for strategy, integration and requirements, has said only F-35′s modified with the upcoming Block 4 upgrade would be of use in a fight against a near-peer nation like China.

“I will absolutely say it doesn’t make sense to buy more of the aircraft that you don’t need,” he told Defense News in March. “So when Congress adds in the aircraft — I’ll be the first to say my service has put it on the unfunded request list for some years now. I don’t know exactly when we started doing that; I’d have to go back and look. But that’s probably not the right thing to do.”