The military's caution on shipping thousands of additional troops temporarily to Iraq is based on a fear that the move could be ineffective without bold new political and economic steps.

Commanders also worry that the already stretched Army and Marine Corps would be even thinner once the short-term surge ended. Bush's newly expressed interest in making the military larger would have little impact on that worry because it will take much longer to add substantially to the size of the military.

Generals also question whether sending more troops to Iraq would feed a perception that the strife in Iraq is mainly a military problem; in their view it is largely political, fed by economic distress.

Rep. Ike Skelton (news, bio, voting record), the Missouri Democrat who will become chairman of the House Armed Services Committee next month, echoed those sentiments Tuesday. "I'm convinced the Army and the Marines are near the breaking point," Skelton said, while expressing skepticism that a big troop surge would be worth the trouble.

With Iraq's burgeoning chaos leaving the Bush administration with few attractive choices, it is studying a possible short-term troop increase there. That proposal is the favorite option of some, including potential 2008 presidential contender Sen. John McCain (news, bio, voting record), R-Ariz., and analysts at the conservative American Enterprise Institute, which has strong ties to the administration.

Even the bipartisan Iraq Study Group, which advocated removing most combat troops by early 2008, said it could support a temporary increase if U.S. commanders believe it would be effective. Roughly one-third of the 140,000 American troops in Iraq are combat forces.

Bush revealed his desire to increase the military's size worldwide in an interview with The Washington Post, days after the Army's top general, Peter Schoomaker, warned that the service would "break" without more troops.

The president used no figures, but he said he has asked his new defense secretary, Robert Gates, to produce a plan for increasing the military's size.

The Army announced on Tuesday evening that it will accelerate the planned creation of two additional combat brigades as a means of relieving some of the strain on troops caused by repeated and increasingly frequent deployments to Iraq. Both brigades will be ready to join the rotations to Iraq by next April, 11 months ahead of schedule in the case of one brigade while 17 months ahead for the other.

In the latest indicator of the war's financial costs, White House budget chief Rob Portman told reporters Tuesday it was unlikely this year's price tag would be less than last year's $120 billion. Congress has already approved $70 billion toward this year's price tag, and Bush has long been expected to request an additional $100 billion or more in February.