That leg the Democrats are standing on? It belongs to Senate Finance Chairman Max Baucus (D-Mont.), whose health care reform bill has finally given President Barack Obama and the Democratic majority in Congress something to crow about.

[IMGCAP(1)]The Republicans are doing their best to amputate.

Finance is set to report Baucus’ bill out of committee today, and the leadership-led negotiations to merge the package with legislation previously approved by Health, Education, Labor and Pensions Committee should start immediately thereafter. But the next phase of political jockeying over health care reform had begun almost before the ink

was dry on the preliminary, deficit-neutral cost estimate of $829 billion over 10 years bestowed on the Baucus bill last week by the nonpartisan Congressional Budget Office.

Republicans moved to discredit the score as gimmicky, built on huge tax increases and just flat-out inaccurate, while Democrats — particularly those who were often the most frustrated with Baucus’ insistence on moving deliberately and crafting a deficit-neutral bill with GOP input — referred to it as a game-changer. This fight should carry over into this week, with its staying power highly dependent on whether the forthcoming merged floor bill receives a similar, political boost from the CBO.

“I think this was the biggest shot in the arm that Democrats got for health care in a very long time — very long time,— Senate Democratic Conference Vice Chairman Charles Schumer (N.Y.) said Thursday. “I think one of the major things Americans are looking for is, Is this bill in control — is it in control of cost? Does it add to the deficit? CBO gave a resounding Good Housekeeping Seal of Approval on those grounds. That is going to help us immeasurably.—

Republicans, of course, are having none of this, arguing that the CBO score given to the Baucus bill changes nothing, partly because of its looming merger with the very expensive, very left-leaning HELP bill. The HELP legislation includes a very robust, national public insurance option; the Finance bill proposes much less costly, voluntary nonprofit medical cooperatives.

Additionally, Senate Budget ranking member Judd Gregg (R-N.H.) released documentation charging that the Finance legislation would be a free-spending deficit machine after it is fully implemented in 2014 — a theme that several GOP Senators have chosen to run with.

“In many ways, the score of the CBO on the Baucus bill is irrelevant,— National Republican Senatorial Committee Chairman John Cornyn (Texas) said. “I can understand the sort of popping champagne corks with the preliminary score on the conceptual language in the Baucus bill. But it’s only a piece of the story, and it really, I think in the long run, will be irrelevant to what we ultimately have to vote on.—

The Baucus bill is not a panacea for the Democrats, given their division over the public insurance option and the uncertainty of how the Finance-HELP merger will play out. Key Democrats, such as Sen. Chris Dodd (Conn.), who led the markup of the HELP bill, continue to insist that CBO scores aren’t everything — that a reform bill must be transformative, even if that means spending a little money.

But the Finance package has given Democrats some breathing room to make their case that they are on track to deliver health care reform that won’t break the bank — something they’ve been arguing for months with little supportive evidence to point to. Even some House Democrats have taken to touting the legislation.

And at least there is one Democratic bill out there that theoretically adheres to Obama’s demand that reform be deficit-neutral and not cost more than $1 trillion.

“The president has made it clear that we cannot add to the deficit in the name of reform,— Senate Majority Whip Dick Durbin (D-Ill.) said. “The Finance bill as scored by the Congressional Budget Office not only meets the president’s target, it generates some $91 billion for the Social Security trust fund, which is very positive in terms of fiscal argument.—

Beginning in July and surging in August, Republicans’ political standing and push to defeat the Democrats’ health care agenda gained steam, particularly because of the CBO scores given to the health care reform bills drafted by HELP and three House committees. The public recoiled at the predictions of deficit spending and trillion-dollar-plus price tags, which led to doubts about other Democratic health care proposals, ultimately pushing voters into the ideological camp that the GOP has occupied from the outset of the reform debate.

But now that the Democrats can credibly, if albeit temporarily, point to legislation that is projected to expand coverage to millions of uninsured Americans, all while reducing the federal deficit and implementing popular insurance reforms, the Republicans are repositioning themselves — at least somewhat.

It should be noted that the GOP is not changing its argument entirely.

The CBO’s cost estimate of the Baucus bill and its analysis that it would extend coverage to include 94 percent of all Americans notwithstanding, the GOP is maintaining that the health care agenda being pushed by Obama and the Democrats is on track to cause runaway deficit spending, increase health care costs for individuals and families, and result in millions having their insurance taken away or adjusted for the worse.

But given that Republicans cannot simply point to a CBO score as evidence in and of itself that the Democrats’ plans for health care reform are problematic, they’ve moved to challenge the accuracy of the Baucus bill’s cost estimate while dusting off the tax increases argument.

The GOP is charging that, even if the Finance Committee legislation is deficit-neutral — they argue it isn’t — it is only so because it raises taxes on the health care industry that will be passed along to consumers and forces individuals to buy health insurance under penalty of paying a “tax— that would be collected by the Internal Revenue Service.

And then there are the merger negotiations to meld the Finance and HELP bills: Not surprisingly, Senate Majority Leader Harry Reid (D-Nev.) isn’t inviting the press into his office to chronicle the talks, causing Republicans to label the event a backroom deal that circumvents the process before it even gets started. GOP leaders are not getting an invite to the negotiations, although that doesn’t mean some Republicans, such as moderate Sen. Olympia Snowe (Maine), won’t be seen coming and going from time to time.

Senate GOP Conference Vice Chairwoman Lisa Murkowski (Alaska) said the key for her is that her constituents don’t stand to benefit from the Baucus bill, or anything else she has seen out of the Democrats. Expect to hear more of this personalization from the GOP this week — and the next, and the next after that.

“People in my state are still asking: ‘Well, what’s this going to cost me?’ They are not going to read that CBO report,— Murkowski said. “From best I can tell, there’s an awful lot of folks in Alaska — folks from Alaska to Maine — that currently are insured that will see increases to their insurance as a result of the Baucus proposal.—

Many Democratic moderates remain skeptical. But the CBO score attached to the Finance bill looks to help the majority’s effort to build a 60-vote coalition — depending on the outcome of the Finance-HELP merger negotiations. Sen. Evan Bayh (D-Ind.) said the CBO provided more comfort to centrist Democrats who have been nervous about the process and the bill’s overall price tag, although he stopped short of outright endorsing the bill.

“The more uncertainties you resolve, the more likelihood of success,— said Bayh, a key moderate. “Anytime there’s big unknowns hanging out there, that makes action more difficult. And this resolved one of the big unknowns, which is the fiscal impact, which was very important to many of us, including me.—

Reid spokesman Rodell Mollineau said a positive score from the CBO as well as recent comments from prominent Republicans, such as former Senate Majority Leaders Bob Dole (Kan.) and Bill Frist (Tenn.), also have helped boost Democrats. “All the news that has been coming out stands in stark contrast to the [Congressional] Republicans’ plan of keeping the status quo,— Mollineau said.

Emily Pierce contributed to this report.