Senate health care talks entered a crucial stage Tuesday as Sen. Olympia Snowe (R-Maine) was drawn deeper into the negotiations, Democratic moderates jockeyed to position themselves, and Majority Leader Harry Reid (D-Nev.) prepared to make some tough decisions.

Snowe began working closely with Sen. Ben Nelson (D-Neb.) this week, and the two met jointly with Reid on Monday and convened a group of six centrists — including fellow GOP moderate Sen. Susan Collins (Maine) — Tuesday afternoon to talk about health care.

With Reid aiming to finalize the merger of the Finance Committee package and Health, Education, Labor and Pensions Committee bill this week, both Snowe and Nelson said they were looking to shape the final product in hopes of supporting it.

“Both Sen. Snowe and I are cast out there as potentially the 60th vote or something like that,— Nelson said, referencing the number of votes needed to beat back a likely GOP filibuster. “We just thought it was a good opportunity to go in and talk to Sen. Reid and get some idea of what may be happening in terms of the merging of the bills and raising some concerns that we had so he would have that information and be aware of that as he continues the process.—

Nelson has said that he would feel more comfortable supporting a health care bill that has bipartisan support, making Snowe’s — and potentially Collins’— support a possible key to securing his vote.

Snowe said she met with Sen. Tom Carper (D-Del.) on Tuesday to talk about possibly merging her proposal to create a public insurance option as a fallback option and his plan to allow states to create public plans, health insurance cooperatives or other competitors to private insurers.

Snowe described the meeting as a “sort of a give-and-take on the mechanics of our respective approaches,— but she did not appear to have changed her opinion that Carper’s plan does not pass muster with her.

“I think everyone is very familiar with my position. Now, it’s also adding to the conversation about different issues, and also learning more,— Snowe said of the conversations she’s had with Democrats. “I’ve learned more and I’m coming up with more suggestions for how best to accomplish some of the objectives such as affordability.—

Snowe said she and Nelson told Reid on Monday “don’t rush it— and to wait for a cost estimate from the Congressional Budget Office before bringing any merged bill to the floor.

Senate leaders and the White House appear to be working overtime to secure the votes of moderates, and centrists seem to be feeling the heat.

“Clearly the focus is on the centrists right now,— one senior Senate Democratic aide said.

Democratic Senatorial Campaign Committee Chairman Bob Menendez (N.J.) agreed that centrists “are not disproportionate in the process.—

But most Democratic moderates did not appear to be moved by a Washington Post-ABC News poll that showed 57 percent of the American people support the public insurance option being pushed by the party’s liberals.

“I’m persuaded that the people want some form of a potential public option to protect themselves but they like it better when it’s at the state level,— Nelson said. “And I’m also persuaded that a lot of people just think it sounds like a good idea without knowing the details of it.—

Nelson said he was optimistic about the meeting he and Snowe scheduled with Sens. Mary Landrieu (D-La.), Joe Lieberman (ID-Conn.), Blanche Lincoln (D-Ark.) and Collins in the late afternoon. “One of the best things we’ve got going right now is people are so focused they’re communicating,— he said. “They’re not all trying to posture or position or what-have-you but trying to learn more about what the implications are if the merged bill is of this nature or of that nature.—

He added that the goal is not necessarily to band together to press for specific issues, but allowed that it may happen.

“We may find that there are common points, but we haven’t set out necessarily to do that,— Nelson said. “It’s been more trying to enlighten one another about what our concerns are.—

Besides the meeting Snowe and Nelson arranged, Finance Chairman Max Baucus (D-Mont.) met with centrists Tuesday as well.

Baucus, who has been meeting with various groups and individual Senators, said the centrist meeting was designed to “just go over the bill, what they want and don’t want.—

Amid the flurry of centrist meetings, Reid prepared to meet again Tuesday night with White House officials, Baucus and Sen. Chris Dodd (D-Conn.), who shepherded the HELP panel’s bill through committee in the absence of Chairman Edward Kennedy (D-Mass.). Kennedy died in August.

Dodd declined to give details of what policy proscriptions the group had settled on, but he said the issues are actually not as difficult to resolve as many think.

“We’re working very, very smoothly and actually moving along. If I go into more than that I’ll be negotiating in public and I don’t want to do that,— Dodd said.

But pressed about whether leaders had moved from the listening stage — where they were soliciting ideas from individual Members — to actually writing up compromise proposals on the public option, Dodd said, “We’ve done a lot of talking. Now, we’re going to make some decisions. So decisions are being made.—

Meanwhile, the House also made progress on bringing Democrats together for a health care overhaul.

Speaker Nancy Pelosi (D-Calif.) said preliminary estimates from the Congressional Budget Office showed the various approaches that leaders submitted all produced bills that are fully paid for and deficit-neutral. “So we’re very happy about that, because that gives us the freedom of choice now. That’s what we were waiting for,— she said.

Leaders huddled Tuesday evening to discuss the numbers but declined to release them in advance of a presentation to the Democratic Caucus set for Tuesday night. House Majority Leader Steny Hoyer (D-Md.) nevertheless confirmed that the estimates showed the bill clocking in at less than $900 billion over 10 years, the target price tag set by the White House.

Tory Newmyer contributed to this report.