Washington ? Robert Gates is on a roll. Question is, how long will it last?

The politically savvy defense secretary scored big legislative wins when the Senate voted convincingly to end production of the high-priced F-22 jet fighter and killed an aircraft engine project that he says isn’t needed.

Gates, a Republican holdover from the Bush administration, is on a campaign to change the way the Pentagon does business. In his sights are unnecessary or financially troubled weapons that siphon money away from the troops and gear required for irregular wars being fought in Afghanistan and Iraq.

Yet getting Capitol Hill to go along with further deep cuts to big-ticket programs remains a huge challenge as lawmakers claw to protect the jobs these projects create in their states and districts. Others have serious disagreements with the Obama administration’s strategic choices.

Case in point: House lawmakers want to spend hundreds of millions of dollars for equipment Gates doesn’t want, including more than $400 million for the VH-71 presidential helicopter that the Pentagon wants canceled for being behind schedule and vastly over budget.

“It’s the rarest occasion when a mature weapons system, with all the contracts and subcontracts, is terminated by the Congress of the United States,” Republican Sen. John McCain, who voted in favor of killing the F-22, said recently.

Those hoping the defense budget will be purged of Cold War-style weapons look to be disappointed.

Iran and North Korea are perceived threats in the short run, and superpowers China and Russia still loom as potential threats over time. That means the U.S. arsenal will remain loaded with aircraft carriers, ballistic missiles, nuclear submarines, tanks and long-range bombers like the durable B-52 of Cold War-vintage.

What Gates wants is a better balance between the heavy weapons for a large-scale war and the needs of ground troops going into their ninth year of combat against unconventional foes. For too long, he and his senior advisers have argued, those pressing demands have taken a back seat.

“It would be nice to win our current wars,” Michael Vickers, the Pentagon’s top special operations official, said Thursday.

The grounding of the

$65 billion F-22 program that played out last week was aided by special circumstances, according to defense policy analysts.

The Obama White House used substantial political capital to stop F-22 production at 187 aircraft, threatening to veto any legislation that included money for more new planes. It’s unlikely such an effort will often be repeated given the stuttering economy, health care reform and other serious challenges the administration needs Capitol Hill’s help with.

“They’ve got bigger fish to fry,” said Loren Thompson of the Lexington Institute in Arlington, Va.

Lockheed Martin, the large and influential defense contractor that makes the F-22, didn’t lobby to keep the production line open. That’s perhaps because the company also builds the F-35, an aircraft built for ground attack missions that Gates says is better suited for the uncertainties of unconventional warfare.

The Air Force, Navy and Marine Corps plan to buy more than 2,400 F-35s.

And the Air Force’s top leadership, which backed Gates on the F-22, may not be so cooperative with other moves to drop major weapons from its budget.

“It’s very hard for the stars to align in a constellation that allow a hardware program to be terminated,” said Gordon Adams, a former Clinton administration budget official who specializes in defense issues. “They just happened to align very nicely here.”