Washington ? Keep going. You don’t have to fix all of it now. Just please don’t let it stall.

That’s the essence of the message that Senate Democratic leaders have for their Finance Committee senators, who plan to start voting Tuesday on a remake of the nation’s health care system.

Democrats on the pivotal committee are disappointed with the bill from the chairman, Sen. Max Baucus, D-Mont. Republicans see a chance to deliver a stunning blow to President Barack Obama’s top domestic priority.

The stakes are so high because this isn’t just another committee.

The 23-member panel is a microcosm of the Senate, the narrow gate through which legislation to cover the uninsured and try to control medical costs has to pass. If the committee can’t produce, then the ability of Obama and the Democrats to pass a bill this year will be seriously questioned.

“If it can’t get through the Finance Committee, the mountain that has to be climbed is a much higher mountain, and I don’t know whether they’ll have the ability to climb that mountain,” said Christine Ferguson, a Senate GOP health aide during the Bill Clinton-era health care debate. Now a George Washington University professor, Ferguson was part of an effort to find a bipartisan deal.

Baucus, an optimist by nature, says he has the votes. “Oh, yeah — no doubt,” he says.

But last week the chairman stood alone as he explained and defended his 10-year, $856-billion plan.

No Democrats joined him in front of the media — not even Sens. Kent Conrad of North Dakota and Jeff Bingaman of New Mexico, who spent months working with Baucus trying to find a compromise both political parties could support.

The second-ranking committee Democrat, Sen. Jay Rockefeller of West Virginia, promptly announced he couldn’t vote for the bill without major changes. Senators have readied more than 560 amendments.

The Baucus plan would require all Americans to carry health insurance or pay a stiff fine. It would provide subsidies to many middle-class households and expand government health programs for the poor. Insurers could not deny coverage based on someone’s personal health history.

The plan would be paid for with cuts in Medicare and Medicaid spending, as well as a heavy tax on high-cost health insurance plans. Baucus would not create a government plan to compete with private insurers. And workers at larger companies that offer coverage wouldn’t see big changes.

While business and health industry groups generally have said good things about the proposal, core Democratic constituencies are angry.

Unions see the insurance tax as a direct threat to hard-won benefits. Liberals are outraged by the absence of a government insurance plan. There’s widespread concern that Baucus’ subsidies are too meager and will stick hard-pressed households with thousands of dollars in new insurance bills.

“At the end of the day this has to work for families,” said Sen. Debbie Stabenow, D-Mich., a committee member. “The trade-off can’t be that a middle-class family won’t be able to afford the insurance in this bill.”

Baucus can’t ignore such concerns. With 13 Democrats and 10 Republicans, including Kan. Sen. Pat Roberts, on the committee, he doesn’t have much room to maneuver for votes.

‘Fundamental differences’

The committee staff tentatively has scheduled three days of work on the bill, but that may not be enough to handle the deluge of amendments.

Many Democratic amendments are geared to improving subsidies to make coverage more affordable and scaling back or replacing the 35 percent tax on high-cost health insurance plans. Also on their list: adding the public plan favored by liberals, as well as a requirement that employers offer coverage.

Rockefeller is proposing to cap itemized deductions for the wealthiest taxpayers as an alternative to the insurance tax. He also wants to strike the nonprofit insurance co-ops that Baucus has proposed in lieu of a government plan.

Republicans say they’re coordinating their amendments to highlight what Sen. John Ensign, R-Nev., calls “fundamental differences” with Democrats.

Sen. Orrin Hatch, R-Utah, wants to eliminate the federal insurance requirement on individuals, leaving it up to states to decide. The top committee Republican, Sen. Chuck Grassley of Iowa, said Baucus’ insurance requirement and fines as high as $3,800 for going without coverage amount to “a penalty against middle-class Americans.”

Ensign is trying to limit the future reach of the insurance tax. As proposed by Baucus, the tax would be adjusted based on the general rate of inflation. Medical inflation, however, has been rising about twice as fast. Ensign would peg the insurance tax to general inflation, meaning that fewer insurance plans would fall under its grip each year.