Defying skeptics in her party,  House Speaker Nancy Pelosi vowed Sunday to overcome lingering obstacles and pass health-care reform in the House, restoring momentum to President Obama's top domestic priority and order to her own unruly Democratic caucus.

"When I take this bill to the floor, it will win," Pelosi (Calif.) said on CNN's "State of the Union." "This will happen."

The speaker, who has struggled to overcome a series of recent setbacks, raised the stakes by planning to restart talks Monday among bickering Democrats on the Energy and Commerce Committee, one of three House panels with jurisdiction over health care and where the bill stalled last week. Democratic leaders are newly confident that these differences can be resolved, possibly in time to bring a House bill to the floor before lawmakers depart Friday for the August recess, although Pelosi did not commit to a timetable.

The chaos underscores the difficulty of transforming a major sector of the U.S. economy in a single piece of legislation, and also the perils of rushing Obama's first-term priorities through Congress before concerns about the 2010 midterm elections take hold. "What we don't want is for the process to bog down here," senior White House adviser David Axelrod said on the same CNN program. "We want to keep moving forward, and I believe we will."

Although the Senate will not vote on its plan until after Labor Day, a Senate Finance Committee deal this week would reassure several dozen anxious House Democrats who are wary of the more liberal course their leaders have taken on health care. Feeling burned by a tough vote on climate-change legislation that is languishing in the Senate, these House Democrats sparked an uprising last week that Pelosi is struggling to contain.

A health-care victory in the House this week would be a stirring moment for Obama and allow more breathing room for the Senate, where finance negotiators are trying to write a bipartisan bill that must be melded with a separate health committee version. A defeat would be a devastating setback for Obama and Pelosi. Regardless of the outcome, rank-and-file Democrats are bracing for an intense August at home as their constituents are hit with a wave of advertising from business groups opposed to the legislation and liberal interest groups supporting it.

"I think the people are shellshocked," said  Rep. Michael Arcuri (D-N.Y.), linking the recent passage of the $700 billion financial bailout, the $787 billion economic recovery package, climate change and other major bills approved this year. "So much is happening so quickly that what is happening is people are blending it all together," said Arcuri, who was elected in 2006.

Most troubling in the short term is how few in the caucus of 256 House Democrats understand the emerging 1,000-page bill. Leaders organized a five-hour seminar for Monday to brief lawmakers. "The bill is so complex," said Ways and Means Chairman  Charles B. Rangel (D-N.Y.), a co-author. When staff members agreed to hold the session, Rangel said, "response was overwhelming."

The House and Senate are working on proposals that would expand coverage to up to 50 million people over the next 10 years, at a cost of about $1 trillion. Obama has insisted that the legislation be deficit-neutral and that it begin to "bend the curve" of skyrocketing health-care costs. To that end, Congress is seeking to cut up to $500 billion out of Medicare and Medicaid while improving their efficiency. The remainder would be covered by tax increases.

But as they forge ahead, some lawmakers -- particularly the roughly 80 House Democrats elected in the past three years -- are suffering from political fatigue. By the time the three House committees took up health care a month ago, the chamber had already logged nearly 600 votes and approved at least 40 major bills. It also had just survived a bruising debate over creating a cap-and-trade system to curtail climate change, which produced a 219 to 212 victory for Pelosi.

The climate-change win was initially cast as a major Pelosi victory, because of her investment in securing the necessary votes.

Now, however, a significant bloc of Democrats is balking at moving to the health-care debate so soon after a vote that many freshman and sophomore lawmakers consider the most controversial they have cast. Some even fear that the climate-change vote has put health-care reform, a far greater priority for many Democrats, in grave danger.

"I don't know whose decision it was to put cap-and-trade first, but it was a huge mistake," said Rep. Mike Ross (D-Ark.), a conservative leader on the Energy and Commerce Committee. "It's a divisive issue. I felt like we had the opportunity to do one thing before the August recess . . . and everybody agrees we need to reform health care." 

Pelosi defended her decision. "A number of the people who are having a problem now didn't vote for the climate bill," she said. Those include Ross, a leader of the conservative Blue Dog Coalition.

But freshman Rep. Tom Perriello (D), who represents rural parts of central and southern Virginia, voted for the cap-and-trade bill and is urging leadership to give him time to vet the health-care package with his constituents. "You want to come up with your best ideas and take them out on the road and make them better," he said, adding that the climate vote had already "unleashed a full range of emotions" back home.

Pelosi still held out the prospect of a floor vote this week. "The closer we get, the more you will hear about this difference and that difference," Pelosi said. "But I am very confident that we will be on schedule and we will be able to present a wonderful gift to the American people."

House leaders face two rebellious factions: the Blue Dogs, who want more cost savings in the health-care bill, and newly elected Democrats from moderate districts, who are protesting the surtax on wealthy households that would fund about half of the House bill.

Rep. Jared Polis, a first-term Democrat who represents the affluent Boulder, Colo., area, signed a letter with 20 fellow freshmen and one sophomore member objecting to the tax, which would apply to families with incomes of $350,000 and higher. Polis and his allies worry about the tax hitting small businesses, like the thriving Boulder Book Store and the Mountain Sun brewery in his home town.

Polis said he is encouraged that Pelosi is considering revising the surtax provision so that it hits only millionaire households, a threshold Obama endorsed at his news conference Wednesday. But Polis said he still worries about the small-business impact -- a question he knows Republican critics will raise, as well.

In several meetings with the speaker, the freshmen expressed their concern to Pelosi that the bill reinforces the image of Democrats as "the tax-and-spend party of the your grandfather," as Polis put it.

But the dissent has caused friction among Democratic leaders. The more interest House Democrats express in the more narrowly targeted Senate tax provisions, the more irritated Rangel appears. The chairman said he heard only the usual complaints about the surtax before he announced it, and he said he knew nothing about the health-care benefits tax, to be paid by insurers, that the Senate Finance Committee is considering.

"I don't know anything about the Senate. Never have. And they've told me if I can't say anything good, shut up," Rangel said.

But for Rangel and Pelosi, the fate of the House bill may rest with the Senate. At a minimum, House Democrats want to see where talks between Finance Committee Chairman  Max Baucus (D-Mont.) and ranking Republican  Charles E. Grassley (Iowa) will lead. If their efforts result in a bill this week, nervous House Democrats are expected to rally around its more moderate coverage provisions and more aggressive approach to cost savings.

"There are some members of our caucus who feel it's very important," House  Majority Whip James E. Clyburn (D-S.C.) said.

Staff writers Perry Bacon Jr. and Ben Pershing contributed to this report.