The House Armed Services Committee is pressing ahead with a version of the 2013 defense budget that adds billions to President Barack Obama's proposed budget and rejects the administration's call for military base closings.

The committee convenes Wednesday to go through details of a spending blueprint that calls for a base defense budget of $554 billion, including nuclear weapons spending, plus $88 billion for the war in Afghanistan and related counterterrorism efforts.

That compares with the administration's proposed figures of $551 billion plus $88 billion.

Election-year maneuvering over the size of the Pentagon budget is unfolding against a backdrop of worries by Republicans and Democrats alike that the nation's defenses will suffer if lawmakers cannot stave off more than $500 billion in mandatory military spending cuts scheduled to begin taking effect next year.

The military service chiefs, including the chairman of the Joint Chiefs of Staff, Army Gen. Martin Dempsey, have said publicly they support the Obama plan, but some Republicans have suggested the chiefs harbor secret misgivings.

The administration already is selectively cutting $487 billion from the Pentagon budget over 10 years, an approach it calls prudent in light of shrinking combat commitments abroad and concerns about budget deficits at home.

Defense Secretary Leon Panetta has stressed his concern about Congress failing to find a way around $500 billion in additional, automatic cuts to the defense budget over 10 years, starting in January, which he said would require a "meat-ax approach" to savings.

"We are convinced that it would result in hollowing-out the force and inflicting severe damage to our national defense," Panetta told the Senate Armed Services Committee in February.

The House bill challenges the administration's proposal on several important fronts, including a provision that would block planned increases in health care fees for certain military retirees. The administration argues that such increases are overdue and that the savings are needed to preserve spending in other areas.

The bill also would prohibit the Air Force from retiring certain Air National Guard planes, as called for in the administration's plan. Numerous state governors have pushed back hard against the administration's proposed aircraft cuts and reassignments.