Pelosi spoke at the White House after a meeting Wednesday with Obama and the chairmen of several House committees that have had a hand in shaping the House version of the bill.
Differences remain, including over abortion and whether to create a public option for health insurance.
Pelosi, however, said both bills had the makings for great legislation.
The president and congressional Democrats decided Tuesday night to keep the final negotiations as GOP-free as possible by bypassing the traditional conference committee process.
The White House and Democratic leaders in Congress decided to keep the last leg of talks a closed-door affair. They concluded that the House will work off the Senate's version, amend it and send it back to the Senate for final passage, according to a House leadership aide, speaking on condition of anonymity in order to discuss the private meeting.
The move streamlines the process to avoid Republican efforts to slow it down.
But Republicans aren't giving up yet. House Minority Whip Eric Cantor, R-Va., on Wednesday released a list of 37 House Democrats he claims can be persuaded to vote against the final bill. Cantor noted that Democrats can't afford to lose one of the 60-vote coalition they assembled in the Senate and can't afford to lose more than two of the 220 votes they assembled on the House side.
"I still believe there is an opportunity to prevent this bill -- a bill that will fundamentally alter the relationship between patients and doctors, harm seniors, and impose massive taxes and mandates on small businesses -- from becoming law," he wrote. "If we can convince enough of these 37 members (along with the 39 Democrats who already voted no) to reconsider and switch their position on the bill, I know that we can defeat this government take-over of our health care before it becomes law."
Cantor listed House Democrats who are known to have anti-abortion views as well as Democrats who represent a lot of seniors enrolled in Medicare Advantage. The Republican argued that proposed cuts to Medicare Advantage and potentially "weakened" language on restrictions for abortion funding could put those Democrats in play.
Obama is expected to meet with top House Democrats Wednesday afternoon, as they craft strategy well before Congress returns. The aim is to get a final bill to Obama's desk before the State of the Union policy address sometime in early February.
Democrats reacted defensively to criticism that they are taking the final, most crucial stage of the debate behind closed doors, contending they've conducted a transparent process with hundreds of public meetings and legislation posted online. Republicans seized on a newly released letter from the head of the C-SPAN network calling on congressional leaders to open the final talks to the public, and cited Obama's campaign trail pledge to do just that.
Asked about that promise, House Speaker Nancy Pelosi remarked, without elaboration: "There are a number of things he was for on the campaign trail."
Facing the need to maintain a tenuous 60-vote coalition in the Senate, House Democrats likely will have to give up on starting a new government insurance plan to compete with the private market, something that's a nonstarter with Senate moderates. In its place they hope for more generous subsidies for lower-income families to buy health insurance.
Obama agreed at Tuesday evening's meeting to help strengthen affordability measures beyond what's in the Senate bill, the aide said.
Pelosi suggested Tuesday that House members wouldn't insist on the government plan as long as the final bill provides "affordability for the middle class, accountability for the insurance companies ... accessibility by lowering cost at every stage."
"There are other ways to do that, and we look forward to having those discussions," she said.
House Democrats want the Senate to agree to language revoking insurers' antitrust exemption as a way to hold insurance companies accountable in absence of direct government competition, said Rep. Chris Van Hollen, a member of the House leadership.
The bills passed by the House and Senate both would require nearly all Americans to get health insurance coverage and would provide subsidies for many who can't afford the cost, but they differ on hundreds of details. Among them are whom to tax, how many people to cover, how to restrict taxpayer funding for abortion and whether illegal immigrants should be allowed to buy coverage in the new markets with their own money.
Concerns about affordability are paramount. Major subsidies under the bills wouldn't start flowing to consumers until 2013 at the earliest. Even with federal aid, many families still would face substantial costs.
The House bill would provide $602 billion in subsidies from 2013-2019, covering an additional 36 million people.
The Senate bill would start the aid a year later, providing $436 billion in subsidies from 2014-2019, and reducing the number of uninsured by 31 million.
"Affordability is a critical issue," Van Hollen said.
But sweetening the deal for low- and middle-income households could require more taxes to pay for additional subsidies. And the House and Senate are also at odds over whom to tax. The House wants to raise income taxes on individuals making more than $500,000 and couples over $1 million. The Senate would slap a new tax on high-cost insurance plans. Although the Obama administration supports the Senate's insurance tax as a cost-saver, labor unions, which contribute heavily to Democratic candidates, are against it.
The House may end up accepting the insurance tax if it hits fewer people than the Senate's design now calls for. There also could be common ground in a Senate proposal to raise Medicare payroll taxes on individuals making more than $200,000 and married couples over $250,000.
The Associated Press contributed to this report.