An EA-18B Growler taxis onto a catapult prior to launching from the aircraft carrier USS Carl Vinson on Dec. 5, 2013. Carl Vinson is currently underway conducting carrier qualifications off the coast of Southern California.

WASHINGTON — It wasn't looking good for the Growlers. The Boeing-made fighter jets, used to jam enemy radar, were left out of the Pentagon's budget for next year. And with spending strictly limited by a budget cap, the plane seemed headed for extinction.

But in reality, the Growlers aren't dead yet. Like dozens of other programs, the EA-18G Airborne Electric Attack Aircraft, as they're officially known, have ended up on something called the "unfunded priorities list," an inventory of what the Pentagon would like to buy if it had several extra billion dollars to spend.

Securing a spot atop the Navy's list has given Boeing hope, and the company has launched an aggressive lobbying campaign, in the media and on Capitol Hill, where it has urged lawmakers to come up with $2.1 billion for the 22 airplanes the Navy has said it would like to buy.

As Congress begins to wade through the Pentagon's budget this week, deciding what stays and what goes, lawmakers will face a temptation that it has not seen in the past few years: robust wish lists, loaded with all sorts of shiny, new things they supposedly cannot afford to buy.

Former defense secretary Robert Gates had all but banned the lists, which allow the services to bypass the secretary's office and go directly to Congress. But now, in an election year, they are back — resurrected by a member of Congress — stark reminders of how even in an era of tightened budgets, defense spending exerts a powerful pull.

Critics say dangling page upon page of ships, aircraft and training programs before Congress can act as a gateway to the kind of out-of-control spending that lawmakers have vowed to curtail. If the items were such a priority — or a "requirement," as they are sometimes called — then they would have been funded in the first place, they say.

Or put another way, said American University's Gordon Adams, an expert on defense spending, they are like telling a 4-year-old he absolutely can't have a lollipop and then asking: But if you could have a lollipop, what flavor would you want?

"The services game the system with the expectation that there will be more money," Adams said. "So they don't make the hard choices. Nothing has been done to truly suppress the appetite of the services. . . . It's an undisciplined and chaotic process right now."

For the second year in a row, the base defense budget is held under a strict budget cap, $496 billion, that is supposed to force Congress and the Pentagon to make tough choices about what to fund. That figure is several billion dollars lower than just a few years ago. Rep. Howard "Buck" McKeon, R-Calif., chairman of the House Armed Services Committee, requested the supplemental lists earlier this year, saying that "defense funding is substantially underfunded to meet national security requirements."

He wanted his fellow members to see what options were available as they begin marking up the budget starting Wednesday.

"You can't really understand the trade-offs until you see what landed on the cutting-room floor," said Claude Chafin, a spokesman for the committee.

Budget experts say that if Congress wants to give in to the temptation of the list, it has a mechanism for freeing up cash to buy things: The Overseas Contingency Operations fund, which pays for the wars in Iraq and Afghanistan, can be used as a buffer.

Even though the wars have wound down, the war fund has remained robust. Last year, it hit about $85 billion, nearly $6 billion more than the Pentagon asked for. And Congress has used that additional money to make room for items in its base budget, said Todd Harrison, a defense analyst at the Center for Strategic and Budgetary Assessments.

He estimated that the Defense Department last year moved $20 billion worth of expenditures from its base budget to the war fund, and then Congress shuffled over $10 billion more. That freed up $30 billion in buying power for the base budget.

"It's a big shell game, but Congress wrote this loophole into the law and both Congress and the Pentagon have shown they are willing to use it," he said.

This year, the war-funding budget has not been set yet. But the Obama administration has put in a placeholder for about $80 billion.

Boeing says it does not know where Congress would get the money to pay for the Growlers — only that it should come up with the funds somehow. The planes serve a crucial function, company officials say, jamming enemy radars so that U.S. planes can attack without being detected.

In lobbying for its planes, Boeing has taken aim at Lockheed Martin's F-35 Lightning II, the Joint Strike Fighter aircraft that has become the most expense weapons system in the Pentagon's history and is eating up much defense spending.

Boeing says that only the Growler can provide true "stealth," because it can help planes fly undetected across the electromagnetic spectrum. And as radar detection becomes more sophisticated and prevalent, company officials say, the Growlers are vital components of air combat.

"It's become increasingly important for the U.S. and its allies to be able to control and dominate the radio frequency waves if you're going to protect your troops and win a fight," said Mike Gibbons, a Boeing vice president. "There is no other asset like it."

The company has lined up support in Congress, including Sen. Claire McCaskill, a Democrat on the Senate Armed Services Committee. She represents Missouri, the state where the Growlers are manufactured, but said her support has nothing to do with parochial interests.

The need for what is called electronic attack "is going to explode," she said during a recent congressional hearing. "And I just can't imagine this isn't going to be one of our highest priorities in terms of our readiness and capability for decades to come, because of the potential that's there."

Lockheed has pushed back against accusations that its aircraft can be outperformed in any aspect, saying in a statement that the "package of capabilities in the F-35 is unprecedented in military aviation. Extensive analysis and flight test of the survivability of the F-35 with its combination of stealth, advanced sensors, data fusion, sophisticated countermeasures, and electronic attack demonstrate conclusively its advantages over earlier generation aircraft."

Bethesda, Maryland-based Lockheed also has support in Congress, including more than 100 members who wrote to McKeon this month, urging his committee to restore funding for the eight F-35s that were left out of President Barack Obama's budget request because of the spending cuts known as sequestration. While not mentioning the Growler, the letter lauded the F-35's "unmatched stealth" as a key part in "achieving air superiority in future surface-to-air and air-to-air" fights.

Boeing says that if its request goes unfunded this year, it will not be able to sustain production and will have to shut down the entire line, which includes the F/A-18 Hornet, the primary fighter plane for the Navy. That would mean if the Pentagon decided it did want more Growlers in years to come, they would not be available.

In an interview, Rep. Adam Smith of Washington, the ranking Democrat on the House Armed Services Committee, said funding the full request "is going to be extremely difficult to accomplish in the budget environment."

But he said he does think that Congress "can come up with a number to keep the line alive."

