WASHINGTON -- After months of bipartisan negotiations on a health care overhaul bill, Sen. Max Baucus, D-Mont., chairman of the Senate Finance Committee, on Tuesday made it official that he's moving ahead without Republican support. He told reporters he intends to unveil a detailed outline of legislation on Wednesday and convene the committee next week to vote on it.

Despite numerous gestures to Republicans, Baucus fell short in his quest to assemble a coalition of senators from both parties behind his plan.

Baucus' proposal is certain to shun the liberals' call for the government to sell insurance, and rely instead on co-ops to offer coverage in competition with private industry. His approach includes a requirement for individuals to buy insurance, with financial penalties for those who don't. Rather than a mandate for larger businesses to provide coverage for employees, they would be required to defray the cost of any government subsidies their employees would qualify for.

"I expect by the time we finally vote in the committee, there will be Republican support," Baucus said, but other Democrats said they believed Sen. Olympia Snowe, R-Maine, may be the only one of the panel's 10 GOP members to vote for the package. Sens. Charles Grassley of Iowa and Mike Enzi of Wyoming have also been involved in the marathon negotiations, but both have raised late objections.

Liberals, too, expressed their unhappiness.

"The way it is now there is no way I can vote for the package," Sen. Jay Rockefeller, D-W.Va., said on a conference call with reporters.

Grassley applauded Baucus' effort at bipartisanship, but complained that Senate Democratic leaders and the White House had imposed an artificial deadline on the negotiators and that Democratic leaders "haven't made a commitment to back a broad bipartisan bill through the entire process."

"It looks like we're being pushed aside by the Democratic leadership so the Senate can move forward on a bill that, up to this point, does not meet the shared goals for affordable, accessible health coverage that we set forth when this process began," Grassley said in a statement.

He cited Republican concerns over cost, taxpayer funding for abortion services, medical malpractice and subsidies for illegal immigrants in any health care bill.

"We've been clear from the start that we're willing to stay at the table," Grassley added. "There's no reason not to keep working until we get it right."

Whatever the difficulties, Democrats appeared to gain precious political ground with word that the Massachusetts Legislature could begin voting this week on legislation permitting Gov. Deval Patrick to appoint an interim replacement for the late Sen. Edward M. Kennedy. That would give Democrats a 60th seat in the Senate, and help them overcome any filibuster mounted by Republicans.

Congressional Democrats are grappling with President Obama's unexpected call for immediate access to insurance for those with pre-existing medical conditions, as well as richer Medicare drug benefits than envisioned in early versions of health care legislation.

Additionally, Obama's pledge in last week's prime-time speech to hold the overall cost of legislation to about $900 billion over a decade has spread concern among House Democrats, who have long contemplated a costlier measure.

Yet another late complication, according to several Democrats, is the president's statement that he will not sign a bill "if it adds one dime to the deficit, now or in the future, period. And to prove that I'm serious, there will be a provision in this plan that requires us to come forward with more spending cuts if the savings we promised don't materialize."

The $900 billion target is "very difficult," Rep. Charlie Rangel, D-N.Y., chairman of the House Ways and Means Committee, said Tuesday. "This is reducing coverage for poor and working people."

Rangel spoke of other "restrictions the president has given in his speech," commenting after senior House Democrats pressed top administration officials in a private meeting for an explanation of Obama's $900 billion price tag.

Obama outlined his conditions in last week's speech and an accompanying fact sheet posted on the White House Web site as Democrats point toward votes in the House and Senate this fall.

Obama's decision to detail terms for health care legislation came after months of public deference to lawmakers.

Neither the bill making its way to the House floor nor two companion measures in the Senate included an interim program to assure coverage for consumers with pre-existing medical conditions. Instead, the bills would have waited until 2013, when numerous consumer protections are envisioned.

Sen. Kent Conrad, D-N.D., said the six-member bipartisan group of senators was working at the last minute to meet the president's request. Another official, who spoke on condition of anonymity, said it involved creation of a high-risk insurance pool, beginning in 2010.

No details were available about costs, either to the consumer or the government.

In the House, a spokesman for the Ways and Means Committee said legislation does not include Obama's request for immediate availability of insurance for those with pre-existing medical conditions. But lawmakers "are currently drafting a provision for inclusion in the final bill," the spokesman, Matthew Beck, added in an e-mail.

Officials in both houses said fulfilling Obama's request on Medicare prescription drug benefits would be considerably more difficult, citing the cost.

Nearly a week after Obama's speech, White House aides have not released key details of Obama's various other proposals, including their cost.