The White House threatened to veto a Republican spending bill that would cut billions from the current year's budget, putting House GOP lawmakers on a collision course as they moved into a second day of debate on the package Wednesday.
The GOP bill, separate from the 2012 budget President Obama unveiled on Monday, covers spending for the fiscal year that ends Sept. 30. It would cut $61 billion from 2010 levels and about $100 billion from the amount Obama requested, but never received, for this year.
As congressional Democrats slammed the GOP proposal as too drastic, the White House put out an official statement threatening to reject it.
"If the president is presented with a bill that undermines critical priorities or national security through funding levels or restrictions, contains earmarks, or curtails the drivers of long-term economic growth and job creation while continuing to burden future generations with deficits, the president will veto the bill," the Office of Management and Budget said in a statement.
Spending legislation must be signed into law by March 4 to prevent a government shutdown that neither side says it wants.
The current legislation would affect domestic programs ranging from education and science to agriculture and parks, and it marks the first significant attack on federal deficits by Republicans elected last fall with the support of Tea Party activists. Passage is likely by week's end in the House, but a frosty reception is expected later in the Democratic-controlled Senate.
Pentagon officials also implored Congress Wednesday not to cut too deeply into military spending.
"We shrink from our global security responsibilities at our peril," Defense Secretary Robert Gates told the House Armed Services Committee. "Retrenchment brought about by short-sighted cuts could well lead to costlier and more tragic consequences later -- indeed as they always have in the past."
Gates said the Pentagon is asking for $553 billion for the budget year that begins Oct. 1, plus $118 billion in war costs. He also is asserting that the Pentagon will face a crisis if the Congress does not pass a new defense budget for the current year or passes one with significantly reduced funding.
However, House Republicans so far have rejected efforts to scale back Pentagon funding in their 2011 budget plan -- the Pentagon would actually get an increase from current levels. The largest proposed cut, an attempt by Rep. Luis Gutierrez, D-Ill., to slice $415 million from production of the V-22 Osprey aircraft, was defeated on a vote of 326-105.
For all the maneuvering, the measure is merely a first round in what looms as a politically defining struggle that will soon expand to encompass Social Security, Medicare and Medicaid, the large government programs that provide benefits directly to tens of millions.
"We know we can't balance this budget simply by reducing nonsecurity, nondefense spending," said Rep. Mike Simpson, R-Idaho, referring to the 359-page bill that would cut $61 billion from domestic programs. "But as the saying goes, the journey of a thousand miles begins with a single step. This is that first step."
The measure is sweeping in its scope, cutting spending from hundreds of domestic budget accounts and eliminating many others.
In a reflection of Tea Party priorities, earmarks are banned in the bill. While Republicans touted their legislation as an essential step toward deficit control, Democrats argued it was dangerous.
"With severe and indiscriminate spending cuts, it goes too far. This legislation will destroy American jobs while harming middle-class families, young adults, seniors and, yes, even our veterans," said California Rep. Nancy Pelosi, the Democratic leader.
The Associated Press contributed to this report.