WASHINGTON -- The M1Abrams tank has survived the Cold War, two conflicts in Iraq and a decade of war in Afghanistan. No wonder: It weighs as much as nine elephants and it’s fitted with a cannon that’s capable of turning a building to rubble from two and a half miles away. But now the machine is a target in an unusual battle between the Defense Department and lawmakers who are the beneficiaries of large campaign donations by its manufacturer.

The Pentagon, facing smaller budgets and looking toward a new global strategy, wants to save as much as $3 billion by freezing refurbishing work on the M1 from 2014 to 2017, so it can redesign the vehicle from top to bottom. Its proposal would idle a large factory in Lima, Ohio, as well as halt work at dozens of subcontractors in Pennsylvania, Michigan and other states.

Abrams manufacturer General Dynamics, a nationwide employer that’s pumped millions of dollars into congressional elections over the past decade, opposes the Pentagon’s plans. The tank’s supporters on Capitol Hill say they’re desperate to save jobs in their districts and concerned about undermining America’s military capabilities.

So far, the contractor is winning the battle, after a well-organized campaign of lobbying and political donations involving the lawmakers on four key committees that will decide the tank’s fate, according to an analysis of spending and lobbying records by the Center for Public Integrity.

Sharp spikes in the company’s donations – including a two-week period last year when its employees and political action committee sent the lawmakers checks for their campaigns that totaled nearly $50,000 – roughly coincided with five legislative milestones for the Abrams, including committee hearings and votes and the defense bill’s final passage last year.

After putting the tank money back in the budget then, the House of Representatives and Senate Armed Services committees have authorized it again this year – allotting $181 million in the House and $91 million in the Senate. If the company and its supporters prevail, the Army will refurbish what Army Chief of Staff Ray Odierno described in a February hearing as “280 tanks that we simply do not need.”

It already has more than 2,300 M1’s deployed with U.S. forces around the world and roughly 3,000 more sitting in long rows at a remote military base in California’s Sierra Nevada mountains.

The $3 billion at stake isn’t a large sum in Pentagon terms; it’s roughly what the building spends in a little more than a day. But the fight over the Abrams’ future, still unfolding, illuminates the major pressures that drive the current defense-spending debate.

These include a Pentagon that’s looking to free itself from legacy projects and modernize some of its combat strategy; a Congress looking to defend pet projects; and a well-financed and politically savvy defense industry with deep ties to both, fighting to fend off even small reductions in the budget now devoted to the military, a total figure that presently composes about half of all discretionary spending.

The M1 Abrams entered service in 1980 but it first saw combat during Operation Desert Storm in 1991, when only seven of them were destroyed, all by friendly fire. In the past decade, however, as hundreds were sent to Iraq and later Afghanistan, a key shortcoming became apparent: Their flat bottoms made them surprisingly vulnerable to improvised bombs.