Democrats controlling the House and Senate are on track to give President Barack Obama a key victory by adopting slightly pared-back versions of his $3.6 trillion budget.

Passage of the companion plans, expected Thursday, would provide the young administration with a symbolic boost, even though the budget blueprints provide little guidance on how to craft subsequent Obama initiatives to reshape the U.S. health care system or combat global warming.

House Democrats are pressing a plan to make it easier to use "fast-track" rules to expedite passage of health care legislation backed by Obama, even as their GOP rivals in the Senate won a key vote Wednesday emphatically rejecting such an approach on global warming.

Republicans in both chambers are putting forward alternatives that are more generous with tax cuts and stingier with spending, but none of the plans — Obama’s, House and Senate Democrats’, or the competing GOP outlines — would succeed in tamping down the deficit much below $500 billion within five years.

Congressional budget resolutions are nonbinding blueprints that set the parameters for legislation to follow. Unlike budget resolutions typically advanced in the first years of a presidency, the 2010 budget plans are remarkably light on detail, offering little guidance on how to pay for a health care overhaul or an extension of Obama’s signature $400 tax credit for most workers.

For their part, House Republicans are offering an alternative that eventually would end Medicare as it is presently known.

Sen. John McCain, R-Ariz., broke with Senate GOP leaders to offer a comprehensive budget plan instead of following their strategy of offering piecemeal changes and not going on record with a plan of their own. McCain’s plan would cut spending, deficits and debt significantly below Obama’s budget.

Much of the debate has centered on how to deal with mammoth deficits and what should be done about them. To a considerable degree, however, both parties are paying little heed to the deficit as they advance their respective agendas.

Neither Obama nor his Democratic allies made major revisions in light of the worsening deficit picture, though Senate Budget Committee Chairman Kent Conrad, D-N.D., pressed to roll back some of Obama’s increases for domestic programs. In 2010, for example, the Senate budget plan would pare $15 billion from nondefense accounts, which still would leave increases averaging 7 percent.

The most contentious question facing Democratic negotiators responsible for reconciling the differing House and Senate versions is whether to use the measures as a precursor to advancing health care legislation under rules that would allow the compromise bill to pass the Senate by a simple majority after just 20 hours of debate.

As a general rule, debate is freewheeling in the Senate and most bills need 60 votes to advance, guaranteeing that the minority party has leverage.

Seeking the upper hand over Senate Republicans, House leaders are insisting on having a filibuster-proof bill at the ready if bipartisan efforts to pass health care fall apart. That effort is being resisted by the Senate, though it seems increasingly clear that the final House-Senate compromise on the budget is likely to allow health care reform to pass on a fast track.

After a decisive vote Wednesday, global warming legislation apparently will not advance on such a filibuster-proof path. By a 67-31 tally, the Senate adopted an amendment by Sen. Mike Johanns, R-Neb., against allowing controversial cap-and-trade climate change legislation to pass the Senate with fewer than 60 votes. The vote seemed to reflect considerable Democratic skepticism on global warming legislation; 26 Democrats voted for the amendment.

In the House, Republicans unveiled a budget plan that gradually would eliminate the traditional fee-for-service Medicare program, offering a stark — and politically problematic — alternative to blueprints from Obama and his Democratic allies.

The plan would have future Medicare beneficiaries — people 54 and younger — enroll in private health insurance plans and receive a subsidy on their premiums. Benefits would not be changed for people in the program or those 55 or older.

Democrats warned that the GOP proposal would result in sharply higher costs for the elderly as the value of the subsidy fails to keep up with health care inflation.

McCain’s plan is not as bold as his House GOP counterparts in cutting spending, but would produce a $484 billion budget deficit by 2014, compared with $749 billion under Obama’s budget.