WASHINGTON — President Obama is facing misgivings about his policy agenda from inside his own party, with prominent Democrats objecting to parts of his taxation and spending plans and questioning the White House push to do so much so fast.

Obama's strategy is to advance on all fronts. Buoyed by favorable poll numbers, he is moving to jolt the economy with a massive stimulus package, revamp the healthcare system and push the nation toward renewable energy sources.

The president scored a major victory with the passage of his $787 billion stimulus package. But holding together a Democratic coalition to pass the rest of his program may prove difficult.

Obama's party is peppered with legislators from conservative districts who are wary of a budget proposal that includes tax increases and deficit spending, even if tax cuts are also part of the plan. Already, Republicans have targeted some Democrats with advertisements pressuring them to reject Obama's plans.

Complicating matters, Obama is asking the political system in Washington to absorb a slew of legislation and policy shifts rivaling what President Franklin D. Roosevelt put forward 76 years ago. Going "all-in," in poker terms, puts a strain on a legislative system used to a more incremental approach.

"The hardest part of this is Congress' digestive track, which is rather challenged. We're not used to this," said Rep. Jane Harman, D-Calif.

Fissures among Democratic lawmakers already have emerg- ed. Rep. Eric Massa is a Democrat in a rural New York district where dairy farms and wineries have a major presence. The budget blueprint that Obama released last month would phase out subsidies to farmers with sales exceeding $500,000 a year.

Massa said the cutoff would apply to "every single farm in my district." If the payments are ended, "we're going to have a hard time passing this budget as it is."

"Frankly, I'm not about to abandon America's farms in favor of America's boardrooms. I won't be part of that plan," he said.

Republican operatives hope to encourage defections from Obama's Democratic coalition, zeroing in on potentially vulnerable Democrats from conservative districts. Last month they aired radio ads targeting 30 Democrats who voted for Obama's stimulus plan, including Massa.

They went a step further with freshman Democratic Rep. Tom Perriello, who represents a Virginia district that voted for Republican John McCain in the 2008 election.

The National Republican Congressional Committee took out a TV ad about the stimulus, showing Perriello's phone number and urging people to tell him to "quit wasting our money."

A spokeswoman for Perriello, Jessica Barba, dismissed the ad as "the same old partisan hackery." She added that Perriello supports the president's budget priorities.