And in the longer term, with concern mounting about the government’s $13 trillion debt, a bipartisan deficit-reduction commission is warning that cuts in military spending could be needed to help the nation dig out of its financial hole.

“We’re going to have to take a hard look at defense if we are going to be serious about deficit reduction,” said Erskine B. Bowles, a chief of staff to President Bill Clinton who is a co-chairman of the deficit commission. Senator Judd Gregg, a Republican from New Hampshire who is also on the debt commission, said that if the panel pushes for cuts in discretionary spending, “defense should be looked at,” perhaps through another base-closing commission.

Mr. Gates is calling for the Pentagon’s budget to keep growing in the long run at 1 percent a year after inflation, plus the costs of the war. It has averaged an inflation-adjusted growth rate of 7 percent a year over the last decade (nearly 12 percent a year without adjusting for inflation), including the costs of the wars. So far, Mr. Obama has asked Congress for an increase in total spending next year of 2.2 percent, to $708 billion  6.1 percent higher than the peak under the Bush administration.

Mr. Gates is arguing that if the Pentagon budget is allowed to keep growing by 1 percent a year, he can find 2 percent or 3 percent in savings in the department’s bureaucracy to reinvest in the military  and that will be sufficient money to meet national security needs. In one of the paradoxes of Washington budget battles, Mr. Gates, even as he tries to forestall deeper cuts, is trying to kill weapons programs he says the military does not need over the objections of members of Congress who want to protect jobs.

Mr. Gates enjoys bipartisan support on Capitol Hill and has considerable sway within the administration. But while he may hold the line against major cuts for now, analysts say support for military spending could erode quickly once the Pentagon withdraws a substantial number of troops from Afghanistan.