Washington - Democrats command the votes needed to pass a sweeping health care bill through the House, Speaker Nancy Pelosi said Wednesday, an unexpected statement that quickly drew a biting response from conservative members of the party's rank-and-file demanding changes in President Barack Obama's trademark legislation.

    The House's top Democrat also signaled strongly that lawmakers will soon incorporate a provision to curtail growth in Medicare costs into the legislation, although she said it would be done in a way that "respects the prerogatives" of Congress.

    The White House and conservative lawmakers want to empower an independent commission to order changes in spending within the giant government health care program for seniors, subject to veto by the House and Senate.

    While Pelosi said she has "no question" that Democrats have the votes they need, she stopped short of promising the full House would act on the legislation before beginning a monthlong vacation at the end of July.

    "We are waiting to see what the president says, and what the Senate will do," she said.

    Pelosi spoke as White House officials and Rep. Henry Waxman, D-Calif., chairman of the House Energy and Commerce Committee, met with moderate and conservative Democrats who have stalled progress on the bill, demanding numerous changes as the price of their support.

    Rep. Charlie Melancon, D-La., expressed unhappiness at the Speaker's words. "I've been meeting to death, so if that has been for naught until they counted votes, and just to occupy our time, I'm sorry," he said.

    "I thought we were legitimately having conversations about writing a good health care bill for America."

    Rep. Mike Ross, D-Ark., who also has been involved in days of private negotiations, said he believed the Speaker was mistaken when she said Democrats have the votes to prevail.

    Separately, Democrats on the House Ways and Means Committee met privately to consider changes in the legislation they pushed through last week.

    Across the Capitol, a small group of senators of both parties continued a daily series of meetings aimed at producing a bipartisan agreement. There was no visible sign they were close to an accord, and officials said it appeared that hopes of holding a vote in the Senate before the congressional vacation were gone.

    Pelosi's statement was her most optimistic to date on the prospects for health care legislation, and came a few hours before a prime-time presidential news conference where the president once again urged Congress to act.

    "We will pass reform that lowers cost, promotes choice and provides coverage that every American can count on. And we will do it this year," Obama said in excerpts of an opening statement that the White House distributed in advance.

    Since returning from an overseas trip more than a week ago, Obama has spoken in public on a near daily basis about his desire for legislation to expand health coverage while reducing the skyrocketing growth in costs.

    In recent days, though, public opinion polls have shown a leveling off in support for his proposals, and emboldened Republicans have stepped up their criticism. One, Sen. Jim DeMint, R-S.C. has predicted that health care could turn into Obama's "Waterloo" if the legislation is blocked.

    The president referred to the political struggle, as well. "This isn't about me," he said in the excerpts. "I have great health insurance and so does every member of Congress."

    In an interview with The Washington Post, Obama expressed confidence that both the House and Senate versions of health care legislation would include some provision along the lines he proposed to curtail the growth of Medicare far into the future. He also spoke favorably of a tax on health care benefits if their cost goes up too fast each year. He said the Senate Finance Committee was discussing a variation that "goes after the insurance company, as opposed to directly taxing the benefits."

    Pelosi's remarks were uttered at a news conference designed to showcase the difficulties that can result from a lack of insurance or insufficient coverage, and appeared aimed in part at recovering some of the political momentum.

    "You are a part of history and you are watching the legislative process at work, and it will take some time," she said. "But we are going to do it right and it will lower cost, improve quality, expand choices, be fully paid for and make America healthier ..." she said.

    Democratic leaders have said any legislation would bar insurance companies from denying coverage or charging higher premiums on the basis of pre-existing medical conditions.

    In general, the bills would provide federal subsidies for lower income families unable to afford coverage, part of an effort to dramatically reduce the ranks of the uninsured.

    The House bill includes a provision for the government to sell insurance in competition with private companies, a provision strenuously opposed by industry.

    The legislation appeared on course last week, until Douglas Elmendorf, the director of the Congressional Budget Office, said it lacked steps to control the costs of health care in the future.

    On Friday, Obama called for lawmakers to include a provision to change that, specifically requesting creation of an independent board that would have the power to set payment rates for doctors, hospitals and other providers under Medicare.

    But in a fresh sign of the challenges, the American Hospital Association urged its members to oppose the provision, saying it could "hit future hospital reimbursements hard." The AHA joined other hospital organizations recently in agreeing to cut more than $150 billion over the next decade from projected Medicare payments. Officials could not be reached to say whether that deal might be reconsidered in view of the proposed change to the legislation.

    The administration's legislation, as well as a competing bill backed by Sen. Jay Rockefeller, D-W.Va., would both dramatically reduce the clout that Congress has in setting payment rates, a change that has drawn opposition from numerous lawmakers. At the same time, they are designed to clamp down significantly on future costs.

    Rockefeller's bill, for example, limits Medicare's growth to 1.5 percent a year, until the program is financially solvent, regardless of the rate of inflation.

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    Associated Press reporters Erica Werner and Ricardo Alonso-Zaldivar contributed to this story.