WASHINGTON - Democrats call the Senate's health-care bill a first big step toward insuring more Americans and controlling costs; Republicans counter that it's the first step toward bigger government and higher taxes.

The two parties are locked in a fierce battle to sway public opinion, and whoever wins it will win the health-care struggle.

The next legislative step is expected about 7 a.m. today, when the Senate plans to take a second vote on cutting off a Republican-led debate on the Democrats' $871 billion plan. The first effort passed 60-40 early yesterday on a straight party-line vote; those who favored cloture included all Philadelphia-area senators.

If the Senate passes the bill later this week, as expected, negotiators from both chambers of Congress will begin trying to reconcile the Senate measure with one the House passed last month.

One threat to eventual passage is the public's view of the legislation, said Paul Ginsburg, president of the nonpartisan Center for Studying Health System Change.

It could take several weeks for the conference to produce a bill, and "that's a long time for public opinion to shift," he said, and its success, particularly in an election year, will depend on "how this plays out with the public over the next few months."

Senate Democratic leaders yesterday touted an endorsement from the American Medical Association, which followed some special deals it got in their bill. A 5 percent tax on elective cosmetic surgery procedures was replaced with a 10 percent tax on indoor tanning services; a proposed fee on doctors to enroll in Medicare was dropped; and payment cuts to specialty and other doctors to pay for bonuses to primary-care doctors in underserved areas were eliminated, said the AMA's president-elect, Dr. Cecil B. Wilson.

"America has the best health care in the world - if you can get it," Wilson said at a news conference with Senate Majority Leader Harry Reid (D., Nev.) and other leaders. "For far too many people, access to care is out of reach because they lack insurance."

Signs of what could happen next on health care are mixed.

Elizabeth Carpenter, a health-policy analyst at the center-left New America Foundation, said the two chambers' bills show "pretty broad agreement on a lot."

Under both bills, insurers would be barred from rejecting anyone because of pre-existing conditions. Gone, too, would be the practice in many states of charging women more than men, and insurers would be limited in how much they could increase rates on older people.

Consumers could shop for coverage through exchanges, much as they now scan the Internet for the best airline fares. Most people would have to obtain a certain level of coverage, and would face penalties if they fail to do so.

Both chambers agree on financial help for people having trouble affording coverage; both would provide aid to families earning up to about $88,000 per year.

What could derail the entire effort are areas in which Democratic leaders have struggled for months to find common ground: abortion, taxes, and the public option.

Ultimately, Democrats will write the final bill, because they control 60 Senate seats - enough to cut off extended debate - and 258 of the House's 435 seats. But that means appealing to the approximately 52 moderate-to-conservative Blue Dogs in the House, and to the eight to 12 centrist Senate Democrats.

That's likely to mean important concessions on the three big sticking points.

Already, liberals' yen for a government-run insurance alternative and for giving women more access to elective abortions faded when moderate senators balked.

One of the public option's biggest boosters, Sen. Russell Feingold (D., Wis.) said he realized that without the moderates, the entire bill could be defeated, and "the cost of inaction is simply too high."

Final passage of the Senate bill - requiring a simple majority - is set for Christmas Eve, if Republicans take all the available time. As of yesterday, they said they would.

"I am willing to stay here. The flight that I have is Christmas morning, and I don't plan on changing that reservation," Sen. Bob Corker (R., Tenn.) said after a meeting of GOP senators. "We potentially are getting ready to pass a bill that there's no question in my mind is going to lead to huge deficits down the road."

This article includes information from the Associated Press.