Three months before he was elected president, Barack Obama vowed not only to reform health care but also to pass the legislation in an unprecedented way.

"I'm going to have all the negotiations around a big table," he said at an appearance in Chester, Va., repeating an assertion he made many times. He said the discussions would be "televised on C-SPAN, so that people can see who is making arguments on behalf of their constituents and who are making arguments on behalf of the drug companies or the insurance companies."

But now, as a Senate vote on health-care legislation nears, those negotiations are occurring in a setting that is anything but revolutionary in Washington: Three senators are working on the bill behind closed doors.

Senate Majority Leader Harry M. Reid (D-Nev.) sits at the head of a wooden table at his office as he and Sens. Christopher J. Dodd (D-Conn.) and Max Baucus (D-Mont.) work to merge two competing versions of health-care legislation into one bill. The three men will be joined by top aides as well as by members of President Obama's health-care team, led by White House Chief of Staff Rahm Emanuel. The sessions started on Wednesday and could be completed this week.

The group will make such key decisions as whether to include a government-run insurance plan designed to compete with private insurance companies. The bill passed in July by the Senate Health, Education, Labor and Pensions Committee, which Dodd led while Sen. Edward M. Kennedy (D-Mass.) was ailing, included such a provision, but the legislation passed last week by Baucus's Finance Committee did not.

The bills also differ on how much Americans who do not buy insurance should be fined as the government seeks to get everyone covered.

In the sessions, Dodd in effect represents advocates of the government-insurance option and Baucus represents those less committed to that proposal. The tie-breaking votes are likely to be Reid and, on Obama's behalf, Emanuel. Obama and Reid have said they personally back the government-insurance option but have not ruled out supporting a bill that lacks such a provision.

Although much of the writing of legislation happens in closed-door meetings, congressional Republicans have sharply criticized the ongoing process.

"This bill is being written in the dark of night," said House Minority Leader John A. Boehner (R-Ohio), adding that "the president ought to keep his promise to the American people and open this process up."

"It's ironic that Congressman Boehner would be complaining since he has refused every step of the way to participate in the effort to reform health insurance," Reid Cherlin, a White House spokesman, said in a statement. "The House and Senate have held scores of hearings on health insurance reform -- as Congressman Boehner well knows -- and at the White House we've held an unprecedented series of webcast meetings with key health care stakeholders to gather their input in a public forum."

Baucus played down the private nature of the group's meetings. "In a real sense, all senators who want health-care reform are in the room because we'll be talking to all of them, they'll be talking to us," he said.

The three senators and Emanuel won't be the only ones playing a role in shaping the legislation. Every member of the Senate will have a chance to offer amendments to the bill the three senators write. And even though the final legislation is expected to resemble more closely the version in the Senate, where final passage would require support from more-conservative Democrats, House Democrats have been meeting for weeks on their version of the bill.

The House Democratic leadership and several key chairmen meet daily, and are regularly briefing smaller groups of lawmakers. As in the Senate, House moderates and liberals remain divided over the government-insurance option, which Speaker Nancy Pelosi (D-Calif.) strongly favors.

The House meetings are also not televised on C-SPAN or open to the public. But unlike the Senate negotiations, the House discussions tend to be open to more lawmakers.

"We have meetings and more meetings and gripe sessions," said Anthony Weiner (D-N.Y.). "This process has been almost open to death."

But after weeks of Senate Finance Committee public hearings, the Senate negotiations are now an invitation-only affair in Reid's office. The majority leader is unlikely to expand his group, even as some senators unhappy with parts of the legislation, such as John D. Rockefeller IV (D-W.Va.), have asked to be in the room.

Instead, lawmakers try to influence the three senators however they can. Sen. Charles E. Schumer (D-N.Y.), a close Reid ally, annoyed him recently by publicly pressing the majority leader to include a government-run public insurance option. Moderate Democrats are privately prodding Baucus to defend the approach in the bill passed by his committee.

In addition to being well-versed in health-care policy, some of the negotiators gathering in Reid's office are quite health-conscious. Baucus has run 50-mile "ultramarathons" and wants to complete a 100-mile race. Reid and Emanuel do yoga, and Dodd turned the recent announcement of his prostate cancer diagnosis into a virtual public health campaign.

While fellow lawmakers seek to influence them, Dodd and Reid are dogged by low approval ratings in their home states and are facing reelection next year. As they emerged from a health-care session last week, Dodd and Reid touted the number of uninsured in their home states who would benefit from the legislation.

"All of my polling numbers are good," Reid said, even as polls show him trailing several potential challengers. On Friday, he took the highly unusual step of starting to run campaign ads more than a year before the election.

Reid, in particular, faces a balancing act. As majority leader, he is tasked with shepherding the bill and ensuring that it has the support of conservative Democrats necessary for passage. But liberal activists who could raise money and help him win next year, including the group MoveOn.org, are demanding he aggressively back the public option.

Reid, like the other members of the group, seems prepared to disappoint some people to get the broader bill finished.

"Neither I nor any other senator has the luxury of passing a perfect bill -- I wish we could -- that conforms exactly to his or her beliefs," he said. "But we must act."