It seemed like General Dynamics’ attempt to win the contract was over before it officially began. The company’s protest, arguing the regulations were rigged for its competitor, was flatly dismissed by the Army even before bids were due. Then the company decided not to enter a bid.

But that doesn’t mean it has bowed out of the competition. Behind the scenes, the Falls Church-based company has waged an intense lobbying campaign that it hopes will keep it in the running for at least a slice of the Army contract to build nearly 3,000 Armored Multi-Purpose Vehicles, worth about $10 billion.

For the past few months, it has pushed legislative language that would force the Army to either reopen the bidding or to purchase some vehicles from General Dynamics. So far, the language hasn’t been adopted by Congress. But now, with the issue scheduled to come before the Senate Appropriations Committee, the company is pushing as hard as ever, officials say, in what could be a last-ditch effort that illustrates the importance of landing big-tickets contracts as Pentagon spending tightens

General Dynamics says its vehicle is well suited for the job, and, since it is already in production, could be ready quickly to replace the Vietnam-era M113 vehicles now in use. Company officials would not discuss their lobbying efforts, but said that the Stryker provides a quicker, smoother ride and has been used to evacuate wounded troops in Iraq and Afghanistan with great success for years.

But others say the decision to bypass the bidding and go directly to Congress is an attempt to big-foot battle-tested Army commanders, who should be able to decide what kind of combat ambulance works best without political interference.

“Unfortunately, this is a symptom of a broken system in the way the [Defense Department] acquires systems,” said Todd Harrison, the director of defense budget studies at the Center for Strategic and Budgetary Assessments. “It sets requirements in such excruciating detail that it basically forecloses the opportunity for real competition. And what companies like General Dynamics are doing is trying a back-door around that, through Congress.”

Congress isn’t usually shy about telling the Pentagon it could spend its money better, and it has intervened on at least one other high-profile Pentagon program this year. The Air Force is trying to retire its fleet of A-10 Thunderbolt II, known as the “Warthog,” which it says is past its prime and could be replaced by better, more modern aircraft. But Congress has rallied to the Warthog’s defense, and may likely save the planes for at least another year.

It’s not just big-dollar planes and tanks that get Congress’ attention. Earlier this year, a member of the House Armed Services Committee inserted language into the defense spending bill in an attempt to have the Army buy a certain kind of tactical ladders that were manufactured in his district.

Critics of the process say that military leaders are capable of picking out the equipment it needs, and that Congress should defer to them. But others say oversight is one of Congress’ most important functions, and the members provide a much-needed check, especially given the Pentagon’s record of allowing some weapons programs spiral out of control.

In the case of the armored vehicle, the dispute largely comes down to one key, if obscure, detail: whether the vehicles travel on wheels or tank-like tracks. General Dynamics’ Stryker vehicle has wheels; BAE Systems’ offering, a version of its Bradley fighting vehicle, has tracks.

In a statement, the Army says it conducted a “full and open competition” that did not require companies to offer tracked vehicles over ones with wheels. After meeting with industry officials, it said it relaxed some of the requirements, “which opened up the program even further to competition among multiple platforms.”

But it did say that the AMPV “must be able to maneuver across the same terrain as the M1 Abrams and the M2/M3 Bradleys,” which have tracks.

Now that the Army has gone through the process and has a bid, it is eager to move forward. Splitting up the buy between Bradleys and Strykers would “delay the program by at least two years” and increase development and testing costs by $95 million, the Army says.

But General Dynamics said that since they are already in the Army’s fleet, additional Strykers could be available within a year. The vehicles break down less often and the cost to repair and operate them is far less than a tracked vehicle, company officials said.

The language the company has been pushing could compel the Army to buy Strykers for the vehicles the Army expects to use specifically for combat medical evacuations. That comes to about a quarter of the total.

“The committee is concerned that the Army may waste time and scarce modernization funding by developing a new medical evacuation variant,” the language that is circulating on Capitol Hill says. “The committee notes that the Army already has developed a medical evacuation vehicle based on a wheeled combat vehicle and that this vehicle has successfully deployed in combat.”

It then prohibits the Army from spending any money developing a new vehicle for that mission, ostensibly steering the buy to the Stryker.

BAE Systems, the only apparent bidder on the contract, has countered by saying that its vehicle is the only one that meets all the Army’s requirements. It spent years working with the Army to develop exactly what military commanders felt they needed, company officials say.

“I want to see this competition proceed on the merits of the requirements and not based on legislative influence,” Mark Signorelli, BAE’s vice president and general manager for combat vehicles, said in an interview in April, before the bids were due.

Congress should “perform oversight,” he said. “But I’ve seen some language that would lead me to believe that there may be some that want Congress to engage in the selection of solutions for the Army. … And when I see things that impact the Army’s ability to take care of its soldiers unnecessarily, I find that frustrating.”

So far, General Dynamics has had limited success with its attempts to insert beneficial language into law. The House has adopted language that would require the Pentagon to provide a report on “existing wheeled and tracked combat vehicles that are used for medical purposes.”

But one Congressional aide said there “was no substance” to the language. “It’s simply contractor warfare.”

Soon, the defense spending bill will come before the Senate Appropriations Committee. In a letter to Sen. Richard Durbin (D-Ill.), the chairman of the subcommittee on defense, Sens. John Cornyn (R-Tex.), Kelly Ayotte (R-NH) and John Boozman (R-Ak.) urged him to move forward with the program.

“Suggestions that this program should be delayed are without merit and would unnecessarily delay the delivery of a more survivable and mobile vehicle, placing the lives of American soldiers in future conflicts at risk,” they wrote.

Durbin, however, has remained inscrutable.

“Senator Durbin has been assessing the Army’s plan and other proposals,” Christina Mulka, his spokeswoman, said in an e-mail. “His final position will be made public at the mark-up.”

That’s expected to happen sometime this month.