In the battle of the budget, Speaker Nancy Pelosi (D-Calif.) has emerged as the chief defender of President Barack Obama’s priorities against a more reluctant Senate.

Although Pelosi cut deals with her party’s moderates that slightly rein in Obama’s ambitions, the House budget passed last week hews more closely to the president’s, slicing just $7 billion relative to the Senate’s $15 billion haircut.

More importantly, Pelosi has embraced the hardball tactic of blocking Republicans from filibustering health care — Obama’s top priority.

Pelosi has repeatedly made it clear that she intends to demand reconciliation instructions for health care in negotiations with the Senate, and she has dismissed complaints from Republicans and some Democrats as an inside Washington fight over process.

“What does it mean to the American people? By one process or another, we are going to get them what they want, and that is quality health care that is affordable and accessible to them,— Pelosi told PBS in an interview last week.

Senate Democrats appear to be moving toward accepting Pelosi’s position on reconciliation for health care in a final budget deal, despite the misgivings of senior Senators, including Budget Chairman Kent Conrad (N.D.) and Sen. Robert Byrd (W.Va.).

Senators as well as Pelosi are looking at using the rules as a “last resort— and say they still hope for a bipartisan deal.

But the high-stakes battle comes as Republicans have been digging in against one of Pelosi’s priorities — giving every American the option of a public health insurance plan like Medicare alongside private plans.

“I believe it should have a public option in it for it to really be substantial,— Pelosi said of the health care bill. “I think the best prospect for that to happen is to do it under reconciliation.—

Meanwhile, Senate Majority Leader Harry Reid (D-Nev.), while supportive of the Obama agenda, has less control of his chamber as he is faced with a group of independent-minded centrist Democrats less easily controlled than the fiscally conservative Blue Dogs in the House.

While the highly regulated House floor fight on the budget lacked drama because only substitutes were made in order, the free-form Senate vote-a-rama showed that some parts of Obama’s agenda face a stiff headwind in that chamber.

Although only two Democratic Senators voted against the budget, Obama’s plan for a cap-and-trade system for carbon emissions in particular appears to be in trouble, with about 20 Democrats regularly defecting to support Republican amendments. Pelosi had already cut her own deal with Blue Dogs, promising not to use reconciliation rules for climate change legislation.

But Pelosi also made clear she isn’t going slow on that issue, either, saying she plans to move a climate bill this year regardless of where the Senate is and whether Republicans sign on — and despite some misgivings in her own Caucus.

Other Obama proposals also received thumbs-down votes from the Senate in the nonbinding document, including his plans for keeping the estate tax at 2009 levels and limiting some tax deductions for the rich to pay for health care.

But the core of Obama’s budget — and its focus on energy, health and education — survived both chambers, as substantive amendments aimed at slashing spending and taxes failed.

Presuming an agreement on reconciliation, Democrats could quickly agree on a budget after the Easter recess, with the House starting to move its appropriations bills in May.