WASHINGTON — The Democratically controlled Congress yesterday easily approved a $3.4 trillion spending plan, setting the stage for President Obama to pursue the first major overhaul of the nation's healthcare system in a generation and other far-reaching domestic initiatives.

Despite a persistent recession and soaring budget deficits, Democrats overwhelmingly endorsed the president's request for hundreds of billions of dollars in new spending over the next decade for college loans, early childhood education programs, veterans' benefits and investments in renewable energy aimed at reducing the nation's dependence on foreign oil.

Lawmakers also agreed to use a powerful procedural tool known as reconciliation to advance the president's proposal to expand health coverage for the uninsured — a move that ensures Republicans can't filibuster the legislation.

"This is very exciting," said DeAnn Friedholm, health reform director at Consumers Union, the nonprofit publisher of Consumer Reports. "Some of us have spent our entire careers trying to make sure we have a decent healthcare system, and I think we're on the precipice of being able to get that this time."

The budget resolution didn't win a single vote from Republican lawmakers, who were enraged that the deficit is projected to exceed $1.2 trillion next year. House Minority Leader John Boehner, R-Ohio, called it an "audacious move to a big socialist government" that piles "debt on the backs of our kids and our grandkids."

Still, the measure passed the House by a vote of 233-193 and the Senate 53-43. Only 17 Democrats in the House and three in the Senate voted against it, as did Sen. Arlen Specter of Pennsylvania, who announced Tuesday that he is leaving the Republican Party.

Approval of the budget blueprint was a huge victory for Obama on his 100th day in office, but not a slam-dunk. Lawmakers trimmed his tax-cutting plans, refusing to extend his signature tax credit for working households past 2010 unless it is paid for. They also sliced $10 billion from his spending request for non-defense programs.