David Espo, AP Special Correspondent

WASHINGTON (AP) — Up one day. Down the next. Sometimes legislation to remake the nation's health care system moves in both directions at once. President Barack Obama's top domestic priority is on an unpredictable, midsummer trajectory as the White House and Democrats struggle to bring the complex, controversial issue to a vote in both houses before lawmakers leave town for their August break.

As a sign of the urgency, some House members worked through the night. The Education and Labor Committee debated amendments to health care legislation until about 6 a.m. Friday and planned to resume at 9:15 a.m.

And earlier Friday morning, the Ways and Means Committee voted to approve the tax provisions of the House bill, which would impose $544 billion in new taxes over the next decade on families making more than $350,000 a year. Education and Labor and another House committee were working methodically on separate parts of a bill that would cost roughly $1.5 trillion, which Speaker Nancy Pelosi has vowed to pass by the end of the month.

But Sen. Max Baucus, D-Mont., one of the key senators at work on the issue, said Obama "is not helping us" with his opposition to a new tax on health benefits.

Senate Democratic leaders recently shot down the tax approach, but Baucus, who chairs the Finance Committee, still favors it as a way to pay for a health overhaul. The head of the Congressional Budget Office weighed in strongly in support of the benefits tax Thursday but Obama's opposition makes it that much more difficult for Baucus to revive it.

A bipartisan group of senators said they wanted time beyond the president's early August deadline to pursue an agreement.

And CBO Director Douglas Elmendorf said of the legislation so far, "We do not see the sort of fundamental changes that would be necessary to reduce the trajectory of federal health spending by a significant amount. And on the contrary, the legislation significantly expands the federal responsibility for health care costs."

Slowing the rate of growth for health care spending is one of Obama's twin goals for health care, alongside expanding health care to the millions who now lack it. At its core, the effort involves a requirement for insurance companies to offer policies to all willing buyers, and bars them from charging higher premiums on the basis of pre-existing medical conditions. Legislation would rely on government subsidies to make insurance more available for lower-income individuals and families, and use tax increases as well as cuts in Medicare and Medicaid to pick up the cost.

"I will not defend the status quo," the president said Thursday in New Jersey, where he used a political fundraising appearance for Gov. Jon Corzine to make his latest plea for congressional action.

But a few hundred miles away, all was not well for the president and his allies. Elmendorf's remarks gave ammunition to Republican critics of the bill. Senate Republican leader Mitch McConnell of Kentucky said the budget director's warning should be "a wake-up call," adding, "instead of rushing through one expensive proposal after another, we should take the time we need to get things right."

The CBO director's assessment also underscored concerns that moderate to conservative House Democrats known as Blue Dogs have with the bill backed by their leadership. "We cannot fix these problems by simply pouring more money into a broken system," said Rep. Mike Ross, D-Ark., chairman of the Blue Dogs' health care task force.

Ross and other like-minded lawmakers are demanding changes from Rep. Henry Waxman, D-Calif., chairman of the House Energy and Commerce Committee, one of three panels at work on the measure. Yet there was good news for Pelosi and the administration in hearing rooms not far away.

Republicans on the House Education and Labor Committee failed on party-line votes to delete major portions of the bill, including provisions for the government to offer insurance coverage and create a new way of shopping for health plans through a purchasing exchange. The votes were 29-19.

Republicans were no more successful in the House Ways and Means Committee, where Democrats shot down GOP amendments to eliminate the government insurance option and delete requirements for employers to provide health care. Republicans also failed on amendments to limit medical malpractice awards, and to prevent the government insurance plan from covering abortions. All the votes were largely along party lines.

The Ways and Means Committee voted 23 to 18 to pass the bill, with three Democrats joining all committee Republicans in voting against the bill.

The situation is no less confusing for Obama's legislation across the Capitol.

The Senate Health, Education, Labor and Pensions Committee approved its portion of the legislation on a party-line vote earlier in the week. But Baucus' Senate Finance Committee is days overdue for a promised public drafting session, with no date set to begin.

Baucus has been negotiating for days with Republicans in hopes of achieving a bipartisan compromise. But time clearly is running short, given Obama's personal request for him to deliver a bill by the end of the week.

Baucus and other negotiators ended talks for the week without agreement. "I think it would be prudent for the president to be patient," said Sen. Olympia Snowe, R-Maine, urging Obama to abandon his call for legislation to pass both houses by early August.

The group's task was complicated last week when the Senate Democratic leadership weighed in against a proposed tax on health care benefits.

In one more example of the difficulty of bringing health care legislation to passage, the same tax that those Democrats oppose is seen by Baucus and others as an option that would help achieve the goal of reducing the rapid increases in health care costs. Elmendorf cited that rationale as he recommended the tax in his remarks Thursday.

Associated Press writers Ricardo Alonso-Zaldivar, Stephen Ohlemacher and Erica Werner contributed to this report.