“We need to make tax cuts permanent, and we need to make a commitment there’ll be no new taxes,” Mr. McCain said. “We need to cut payroll taxes. We need to cut business taxes.”

“We need to have a commitment after a couple of quarters of G.D.P. growth we will embark on a path,” he said about the gross domestic product, “to reduce spending to get our budget in balance.”

Republicans plan to test President Obama’s commitment to bipartisanship as his $825 billion stimulus package heads to the floor of the House of Representatives this week, with the House Republican leader saying Sunday morning many in his party will vote no unless there are significant changes to the plan.

“Right now, given the concerns we have over the size of this package and all of the spending in this package, we don’t think it’s going to work,” the House Minority Leader John A. Boehner, Republican of Ohio, said on NBC’s “Meet the Press.” “And so if it’s the plan I see today, put me down in the no column.”

The Republican objections came as President Obama dispatched his top economic adviser, Lawrence H. Summers, to the talk shows to defend aspects of the plan that have come under attack. More details about the stimulus package, the largest of its kind in the nation’s history, have become clear this weekend, as Democrats released a more detailed list of the spending.

Speaking on “Meet the Press,” Mr. Summers, director of the White House’s National Economic Council, said the president was attempting to strike a balance between tax cuts and longer-term initiatives in the bill, like spending on renewable energy and college tuition assistance.

President Obama has pledged three-quarters of the fund will be spent out in the first 18 months, Mr. Summers said in defense of the plan.

“We believe this is a properly sized approach to move the economy forward,” he said.

He also said there might be additional assistance to banks beyond the $700 billion Troubled Asset Relief Program already approved by Congress. Of Mr. Obama’s plans for how the next $350 billion of TARP funding will be spent, he said, “It’s going to be very different than what you’ve seen so far,” with an emphasis on transparency, accountability, and “getting credit flowing again.”

“The next few months are, no question, going to be very, very difficult and it may be longer than that,” Mr. Summers said.

Vice President Joseph R. Biden Jr. said on Sunday he believed the stimulus package would ultimately pass with “fairly strong vote across the board.” “If you notice, roughly 40 percent of this entire package is tax cuts,” the vice president said on “Face the Nation.” “That’s not what the Democrats wanted. And 60 percent of it is spending, economic stimulus. That’s not what the Republicans wanted. But we’ve come a pretty long way already. So there will be, I’m sure, more compromise.”

Mr. Boehner and other Republicans have taken issue with the large chunk of funding in the stimulus package — some $300 billion all told — that will go to shore up the budgets of states. That figure includes billions in state aid to education and such controversial pieces as millions in spending for family-planning initiatives.

House Speaker Nancy Pelosi, speaking on ABC’s “This Week,” said the assistance to states was necessary, including the family-planning funds.

“The family-planning services reduce cost,” she said. “The states are in terrible fiscal budget crisis now, and part of it, what we do for children’s health, education, and some of those elements, are to help the states meet their financial needs.”

She also said House Democrats would consider Republican ideas, judging them “by their ability to create jobs, to — to help turn the economy around, to stabilize the economy, and to see how much they cost.”

Ms. Pelosi said if additional government funding to banks is required, the government should take an equity stake in banks that receive the funds so taxpayers could share in any gains as banks return to health.

If Congress is strengthening the banks, she said, “then the American people should get some of the upside of that strengthening.” But the House Speaker repeatedly objected to the term “nationalization” in describing the government investments.

“Change has to happen in terms of what is done — what the transparency of it is, what the accountability of it is,” she said. “Only then would we be able to pass any additional funding.”