The White House's annual budget request unveiled Monday calls for a NASA spending freeze at $18.7 billion, the same level of funding the agency received in 2010.

The fiscal year 2012 budget request calls for increased spending in science and exploration compared to last year's budget. Funding for space operations would drop nearly $1.8 billion, primarily a result of the retirement of the space shuttle program.

The $18.7 billion funding layout is $300 million less than the draft budget approved for 2011 in the NASA Authorization Act last year and $750 million less than the legislation's blueprint for 2012.

President Obama's budget request must be approved by Congress, where Republican leaders vow to cut NASA funding starting this year. Lawmakers have not passed the federal budget for fiscal year 2011, which began Oct. 1.

The flat NASA budget is in line with the Obama administration's commitment to freeze domestic discretionary spending.

Government agencies are operating under a continuing resolution, a temporary funding measure that keeps offices open near budget levels in the enacted 2010 budget.

In spite of the flat budget, the White House proposes a $350 million increase in funding for commercial crew transportation programs to $850 million next year. The budget request would also initiate development of a heavy-lift rocket and Orion exploration capsule, calling for $2.8 billion in combined spending on those programs in 2012.

The total exploration budget in the White House request is $3.95 billion, $172 million more than the 2010 enacted level. Funding for robotic science missions would increase by $519 million next year in the Obama administration's proposal.

House Republicans on Friday released a proposal to extend the continuing resolution, which expires March 4, through the end of the current fiscal year Sept. 30. The Republican budget calls for a $303 million cut for the rest of 2011 compared to last year's approved budget.

Republican appropriators in the House say their budget would also continue development of a heavy-lift rocket and spacecraft for NASA's exploration program. The new continuing resolution proposed by Republicans would also permit NASA to close out the cancelled Constellation program and limit the agency's cooperation with China.