WASHINGTON - In what is shaping up as one of the most consequential battles of his six-month-old presidency, Barack Obama finds himself in the trenches alongside his former Republican rival, Sen. John McCain, fighting hard to end production of an advance fighter jet that much of the defense establishment considers a wasteful boondoggle.

F-22 Raptor Not only do they face right-wing Republicans long dedicated to the principle that the United States can never have enough weapons to fight any and all possible comers for generations to come.

Normally dovish Democrats, including Massachusetts Sens. John Kerry and Edward Kennedy, are also ranged against Obama hoping to keep production lines open and expanding for the F-22 "Raptor", the world's most advanced and expensive fighter aircraft, each of which costs some 143 million dollars.

At stake is the president's determination to both hold the line on a defense budget that by itself already constitutes nearly half of the world's total military spending and give higher priority to the kinds of weapons that Washington has actually used during the wars of the past eight years versus hi-tech systems that may be more relevant to major conventional conflicts with Russia or China.

Obama has already promised in no uncertain terms to veto any defense appropriations bill that comes to him that includes money for the production of more than the 187 F-22s that are currently on order.

"We do not need these planes," Obama wrote in a letter to McCain and another ally, Senate Armed Services Chairman Carl Levin, earlier this week. "To continue to procure additional F-22s would be to waste valuable resources that should be more usefully employed to provide out troops with weapons that they actually do need."

And he has strong backing from his defense secretary, Robert Gates, who was appointed to that post by none other than President George W. Bush in November 2006.

In speaking out on the issue, Gates has become increasingly caustic about opposition to closing down the F-22 production lines.

"It is time to draw the line on doing defense business as usual," he told the Economic Club of Chicago Thursday, adding that "the more they buy of stuff we don't need, the less we have available for the stuff we do. It's just as simple as that. It ain't a complicated problem."

The F-22 has been a primary target for those forces that have long argued that the Pentagon has spent far too much on sophisticated and costly conventional weapons systems developed during the Cold War for use against a global military rival, such as the former Soviet Union.

Other such systems that the new administration has sought to curb or eliminate include a fleet of new VH-71 helicopters; several unproven missile defense programs; the Navy's DDG-1000 Destroyer, the C-17 transport plane, the Army's Future Combat Systems, the Virginia class submarine, and the V-22 Osprey tilt-rotor aircraft, with projected savings of tens of billions of dollars.

Even with those cuts, the total U.S. military budget - not counting the cost of ongoing military operations in Iraq and Afghanistan - would still come to 534 billion dollars next year. It represents a four-percent increase over current year spending, as most of the savings would be passed along to weapons and equipment, such as remote-controlled Predator drones and "up-armored humvees", Washington has found to be more relevant to unconventional warfare against adversaries such as the Taliban and al Qaeda.

Those kinds of foes represent the kind of "asymmetric" threats that the U.S. military is more likely to face in the short and medium term than the possibility of conventional war with a major regional or global challenger, such as Russia, China, or even Iran, according to a growing number of military analysts in and outside the administration. Even then, proposed 2010 defense budget is weighted heavily toward to conventional weapons systems.

But big defense manufacturers, which have reaped enormous profits from the more-advanced and expensive hi-tech systems, have been mobilizing to prevent the proposed cuts. Already in anticipation of changes, the three biggest companies - Lockheed Martin, Boeing and Northrop Grumman - boosted their multi-million-dollar lobbying budgets by between 54 percent and 90 percent last year, according to the Wall Street Journal.

Of these, the fight over the F-22 is the most prominent. While Lockheed Martin is the primary contractor, Boeing also has a major stake in the plane, and they have been gearing up for a major fight over its future.

The F-22 program currently employs roughly 25,000 workers who are spread out over 44 of the 50 U.S. states in what is a familiar strategy by the major defence contractors to magnify their political clout with both parties in Congress.

Thus, it is not only most Republicans who strongly oppose Obama's plans to shut down production lines; key Democrats, including Kennedy and Kerry, whose states or Congressional districts stand to lose hundreds or even thousands of jobs if production of the jet is capped at 187, have joined also come down against the president.

Thus, late, last month the Senate Armed Services Committee voted 13-11 to add seven new planes to the fleet at a cost of 1.75 billion dollars, with several Democrats crossing the aisle. The addition was put forward by Georgia Sen. Saxby Chambliss whose state hosts Lockheed's main F-22 manufacturing plant.

The full Senate is expected to vote next week on an amendment by Levin and McCain to strip that provision from the bill. In a statement earlier this week, McCain said that, while he was "not without sympathy for parts of the country, including the state of Georgia," that will lose jobs from capping production, "we cannot argue that we can spend taxpayer dollars for weapon systems just to create jobs."

Meanwhile, in an additional challenge to Obama, a key House subcommittee chaired by influential Democrat John Murtha, voted not only to add 12 more F-22s to the fleet, but also to restore some funding the C-17 transport plane and for the VH-71 helicopter, which, among other things, is meant replace the Sikorsky Marine One helicopter that is used by the president.

"We're trying to get at least a few helicopters out of this thing that can be used for the president," Murtha said Thursday. "He's got to have new helicopters. It's that simple."

Informed about the cost overruns associated with the V-21 program, Obama himself said last February that the aircraft was an example of military procurement "gone amok," an assessment echoed by Gates Thursday.

"We ended up with helicopters that cost nearly half a billion dollars each and enabled the president to, among other things, cook dinner while in flight under nuclear attack," he deadpanned.