Washington ? Democrats’ health care bills won’t meet President Barack Obama’s goal of slowing the ruinous rise of medical costs, Congress’ budget umpire warned on Thursday, giving weight to critics who say the legislation could break the bank.

The sobering assessment from Congressional Budget Office Director Douglas Elmendorf came as House Democrats pushed to pass a partisan bill through committees, while in the Senate a small group of lawmakers continued to seek a deal that could win support from both political parties.

Senators involved in the bipartisan talks said Thursday evening they are making solid progress toward a compromise they claimed would hold down costs, addressing the budgetary concerns. But it could take more time to work out difficult issues. And that means that Obama’s timetable for floor votes in the House and Senate before August would slip.

“I think it would be prudent of the president to be patient and allow us the opportunity to work,” said Sen. Olympia Snowe, R-Maine, one of the lawmakers involved in talks led by Finance Committee Chairman Max Baucus, D-Mont.

“I don’t think we should be bound by a timetable that isn’t realistic,” said Snowe, adding that a Senate vote in September would still allow time to finish the legislation this fall.

Baucus said he’s “quite confident” that the group is “making a lot of progress” and would be ready fairly soon.

From the beginning of the health care debate, Obama has insisted that any overhaul must “bend the curve” of rapidly rising costs that threaten to swamp the budgets of government, businesses and families.

Asked by Senate Budget Committee Chairman Kent Conrad, D-N.D., if the evolving legislation would bend the cost curve, the budget director responded that — as things stand now — “the curve is being raised.”

Explained Elmendorf: “In the legislation that has been reported, 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.”

Even if the legislation doesn’t add to the federal deficit over the next years, Elmendorf said costs over the long run would keep rising at an unsustainable pace.

Part of the reason is that Obama and most Democrats have refused to accept a tax on high-cost health insurance plans as part of the overhaul. There’s wide agreement among economists that such a tax would give businesses and individuals an incentive to become thriftier consumers of health care. Finance Chairman Baucus said Thursday that Obama’s position isn’t helping matters.

White House officials played down the significance of the budget director’s assessment, calling it premature. “At the end of the day, we’ll have significant cost controls,” presidential adviser David Axelrod told The Associated Press.

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.”

For the fourth straight day, Obama used a public forum — a political rally for New Jersey Gov. Jon Corzine — to argue for health care overhaul, saying, “It affects the stability of our entire economy.”