Washington ? Breathtaking in its scope and ambition, President Barack Obama’s agenda for the economy, health care and energy now goes to a Congress unaccustomed to resolving knotty issues and buffeted by powerful interests that oppose parts of his plan.

Perhaps the only things as high as Obama’s goals are the hurdles they must clear.

While tackling the economic crisis, he is asking Congress to enact contentious measures that have been debated, but not decided, in calmer times: cut subsidies for big farms; combat global warming with a pollution tax on industries; raise taxes on the wealthy; make big changes to health care, including lower reimbursements for Medicare and Medicaid treatments and prescription drugs.

Standing alone, any one of these proposals would trigger a brawl in Congress and fierce debates outside Washington. Obama wants the proposals done largely in concert, as an interrelated plan to undo major elements of Ronald Reagan’s conservative movement.

Obama outlined the approach in a budget proposal Thursday, a sprawling road map that will require several hard-fought pieces of legislation.

He launched his campaign for the package Saturday with a fiery, populist radio and Internet address that depicted his critics as champions of “the interests of powerful lobbyists” and “the wealthiest few.”

“I realize that passing this budget won’t be easy,” the president said, because it “represents a threat to the status quo in Washington.”

“They’re gearing up for a fight,” he said. “So am I.”

If his rhetoric was tough, the challenges he faces are downright daunting. The economy contracted by a stunning 6.2 percent in the final three months of 2008, its worst showing in a quarter-century. Obama says the crisis calls for gutsy actions, and many groups feel he has delivered.

“We’re struck with how bold and courageous a budget it is,” said James Horney of the liberal Center on Budget and Policy Priorities, which supports the president. “There are a whole lot of things that are going to be extremely difficult because there are very powerful vested interests out there that will fight them.”

Obama is not simply proposing a budget that assumes a jaw-dropping deficit of $1.75 trillion this year, a quadruple increase from the year before. He’s trying to redirect strong currents in American society.

The wealthiest 5 percent would pay a whopping $1 trillion in higher taxes over the next decade, while most others would get tax cuts. Industries would buy and trade permits to emit heat-trapping gases. Higher-income older people would pay more for Medicare benefits. Drug companies would receive smaller profits from the government. Banks would play a much smaller role in student loans.