Senate Democratic Conference Vice Chairman Charles Schumer (N.Y.) confirmed Tuesday afternoon that a hybrid public option is under discussion and said negotiations between liberal and centrist Democrats are going well — but moderate GOP Sen. Olympia Snowe (Maine) was lukewarm on key parts of their budding compromise.

Schumer, who is leading the group’s deliberations, said there are four parts to the blueprint, which would replace the public insurance option included in the bill by Majority Leader Harry Reid (D-Nev.) currently on the Senate floor. Snowe said she disliked a Medicare buy-in for those between the ages of 55 and 64 and a further expansion of Medicaid eligibility.

However, if the group of five liberal and five moderate Democrats can generate a proposal that secures the support of all 60 Senators in the majority, Snowe’s vote would not be needed to close the debate and clear the bill off the floor. Schumer said the group is working as quickly as possible but declined to predict when the talks would conclude.

“All the pieces have to fit together before anyone agrees to anything,— Schumer told reporters. “What we’re trying to figure out here, certainly within our Caucus and then maybe with Olympia, is how much government involvement there should be in health care, how much private involvement. And there are disagreements, and what we’re trying to do is reconfigure that. Not having more of one or less of one, but in different ways that are more acceptable to people.—

Snowe, speaking to reporters separately about the components of the potential Democratic public insurance option compromise, said she finds the national plan that would include a marketplace of insurance companies similar to what is available to federal employees. But she was adamant that expanding Medicare and Medicaid are nonstarters.

“It’s an expansion of government at a time in which we should be moving in the opposing direction, frankly,— Snowe said, following a meeting with Reid. “That’s my deep concern — is about the breadth and scale of this legislation.—

The group of 10 broke for lunch Tuesday but was scheduled to return to the negotiating table later Tuesday afternoon, with plans to work late into the evening if necessary. The participants include Democratic Sens. Sherrod Brown (Ohio) Tom Carper (Del.); Tom Harkin (Iowa); Mary Landrieu (La.); Ben Nelson (Neb.); Jay Rockefeller (W.Va.); and Blanche Lincoln and Mark Pryor, both of Arkansas.

Sen. Joe Lieberman (ID-Conn.), who caucuses with the Democrats and is opposed to a public insurance option of any kind, is loosely affiliated with the group, having sent staff to its meetings.