WASHINGTON - Health care legislation taking shape in the House carries a price tag of at least $1 trillion over a decade, significantly higher than the target President Barack Obama has set, congressional officials said Friday as they struggled to finish work on the measure for a vote early next month.

Democrats have touted an unreleased Congressional Budget Office estimate of $871 billion in recent days, a total that numerous officials acknowledge understates the bill's true cost by $150 billion or more. That figure excludes several items designed to improve benefits for Medicare and Medicaid recipients and providers, as well as public health programs and more, they added.

The officials who disclosed the details did so on condition of anonymity, saying they were not authorized to discuss them publicly.

Some moderate Democrats have expressed reluctance to support a bill as high as $1 trillion. Last month, Obama said in a nationally televised address before a joint session of Congress that he preferred a package with a price tag of around $900 billion.

Obama also said he would not sign a bill that raised deficits, and the CBO estimates the emerging House bill meets that objective. Officials said the measure would reduce deficits by at least $50 billion over 10 years and perhaps as much as $120 billion.

Democrats also said the bill would slow the rate of growth of the giant Medicare program from 6.6 percent annually to 5.3 percent.

"The bill will be paid for over 10 years. It will reduce costs but also will not add a dime to the deficit" in future years, House Speaker Nancy Pelosi, D-Calif., said at a news conference.

Still, Obama's speech provoked enough concern among House Democrats that senior presidential aides were called to a meeting in the Capitol to explain precisely what the president had in mind when he set the $900 billion target.

The figure of $871 billion "is a coverage number. I think the White House has made that very clear. It is a number about coverage," Pelosi said recently when asked about the size of the measure.

Linda Douglass, a spokeswoman for the White House, said, "The speaker is working on a plan that meets with the president's price tag of around $900 billion for health insurance reform and will not add a dime to the deficit."

House Democrats took steps to fulfill another of Obama's goals during the day, announcing their legislation would completely close a gap in Medicare prescription drug coverage within a decade, five years faster than originally contemplated.

In addition, Pelosi said, "as of Jan. 1, 2010, our legislation will give a 50 percent discount for brand-name drugs to recipients in the donut hole and it will reduce the size of the donut hole by $500."

After months of delay, Democrats in the House and Senate are aiming for votes next month on legislation to fulfill Obama's goal of expanding coverage to millions who lack it, banning insurance industry practices such as denying coverage for pre-existing conditions and slowing the growth in health care spending nationally. The House bill will also lift the insurance industry's exemption from federal anti-trust laws, a provision under consideration in Senate negotiations as well.

With time growing short, Pelosi and Senate Majority Leader Harry Reid are struggling independently with the most controversial of all issues involved with health care, proposals for a government-run insurance option to compete with private industry.

In the House, Democrats have tentatively concluded they cannot win passage of the provisions favored by most liberals, one calling for a nationwide government-run plan with payments to doctors and hospitals linked to rates paid by Medicare. It was unclear what fall-back plan was under consideration, but the internal disagreement cast doubt on plans to publicly unveil legislation early next week.

Across the Capitol, Reid, D-Nev., assessed support for a nationwide government-run insurance option that would allow states to opt out of the system. While the plan evidently enjoys a clear majority, it is uncertain whether it can command the 60 votes needed to overcome a threatened Republican filibuster.

Democrats hold 60 votes in the Senate, but one, Sen. Ben Nelson, D-Neb., has spoken out strongly against a so-called public option. A few other members of the rank and file have been non-committal.

One, Sen. Mary Landrieu, D-La., met with Reid during the day and later issued a statement saying she was encouraged that a compromise might be possible. She also added pointedly that she had told Reid about "the unique challenges Louisiana is facing in terms of Medicaid and the special concerns I have about teaching hospitals," a possible signal that easing home-state concerns could influence her vote on the larger, national question of a government-run insurance option.

Also opposed is Sen. Olympia Snowe of Maine, the only Republican this year who has voted for a Democratic-drafted health care bill in committee. As an alternative, she favors allowing the government to step in only if there is insufficient competition in the private insurance industry.

Nor was it clear whether Democrats would be able to enlist additional Republicans. Sen. George Voinovich, R-Ohio, frequently mentioned by Democrats as a potential convert, said in an interview, "We can't afford the health care system that we have right now. And if we can't afford the one we have right now, how are we going to afford another one that's going to cost more money."

For Reid, the question of a government-run option is one of a many thorny issues to be settled before he can bring health care legislation to the Senate floor. He and senior committee chairmen have been meeting with top White House aides in recent days to produce a bill, and hopes of largely wrapping up the work by the end of the week went unfulfilled.

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Associated Press writers Chuck Babington, Laurie Kellman and Erica Werner contributed to this story.