Sen. Kent Conrad’s (D-N.D.) recent attempt to bridge the partisan divide over health care reform may be the best opportunity Democrats have found yet to win over Republicans, but it remains unclear whether the proposal will catch fire with the majority.

Conrad’s idea to set up a health insurance cooperative — rather than a government-run program — started to gain some currency last week, particularly with Republicans opposed to greater government involvement in health care. And the Budget chairman has been negotiating furiously with Republicans and Democrats to make it work.

“I think this is coming together,— Conrad said Friday on MSNBC. “It clearly has momentum.—

But Senate Democratic leaders have been cautious in their appraisal of the plan and have said the co-op option would be acceptable only if it works in the same way they envision a public health insurance plan working — as a competitor to private insurance companies that also lowers health care costs.

Senate Finance Chairman Max Baucus (D-Mont.) said he was entertaining the plan but that ultimately it would have to satisfy some of the Conference’s more liberal Senators.

And he was careful on Thursday to say that Conrad’s idea was not necessarily the path he was going to take in the health care overhaul he is writing as a companion to a Health, Education, Labor and Pensions measure that is set to be marked up this week.

Of Conrad’s plan, Baucus said: “It’s just the one that’s most talked about right now.—

Democratic Conference Vice Chairman Charles Schumer (N.Y.), who sits on the Finance Committee with Conrad, said any co-op would have to be national in scope, would need a large infusion of startup cash from the federal government, and would need to bar insurance industry insiders from serving on its board.

Schumer said he was negotiating with Conrad on behalf of public plan supporters but sounded skeptical about the progress.

“Chairman Baucus has asked me to sit down with Kent Conrad to see if we can use the co-op model to achieve the same goals as a public plan,— Schumer explained Thursday. “There’s just a question mark as to whether we can.—

Indeed, Conrad noted he was already getting blowback from Republicans on Schumer’s demands. The GOP is opposed to the public plan because they consider it a precursor to a government takeover of the health insurance industry.

Conrad said Thursday that several GOP Senators approached him and told him that Schumer’s insistence that the governing board of the co-op be filled by non-insurance types, and possibly government officials, was a problem for them.

Indeed, Senate Minority Whip Jon Kyl (R-Ariz.) told reporters on C-SPAN’s “Newsmakers— that most Republicans see the co-op proposal as just another way to insert government into health care decisions.

“Republicans are very wary of having any kind of alternative government-run [plan] whether they call it a co-op or an insurance company or whatever they call it,— he said.

And there are some influential Democratic voices as well who are already dismissing the idea.

Sen. Jay Rockefeller (D-W.Va.), who last week unveiled a proposal for a robust, government-run, public plan option that is Medicare-based, said in an interview Thursday that he is not a fan of Conrad’s blueprint to create a health care cooperative system in lieu of the public option.

“I’m standing up for what Democrats believe in, or at least ought to believe in,— Rockefeller said, adding about Conrad’s proposal: “It’s nice; it sounds good; it won’t work.—

Rockefeller’s plan already has strong appeal with the liberal base of the Senate Democratic Conference, including some of the leadership.

And Senate Democratic centrists who have been nervous about creating a public plan don’t appear sold yet but say they are keeping open minds.

Sen. Mary Landrieu (D-La.), who this week came out against a public plan, appeared interested in Conrad’s co-op proposal, although she made clear that she was endorsing the bipartisan endeavor not the proposal.

“I’m supporting Sen. Conrad’s efforts to try to bridge a compromise — not in detail, but in concept. And, I think our Democrats are working hard to try to find, you know, to find a way,— she said.

Similarly, Sen. Blanche Lincoln (D-Ark.), who sits on the Finance panel, was guarded when asked about Conrad’s concept. “I think what it has been is a great communications tool for us to bring both sides together,— she said.

But others said they were hopeful some middle ground could be reached.

Sen. Frank Lautenberg (D-N.J.), one of the Senate’s leading liberals, said he would probably be inclined to oppose Conrad’s co-op proposal in favor of Rockefeller’s proposal. However, Lautenberg declined to dismiss the Conrad plan out of hand.

“We’re looking at all the possibilities to see what might be the best plan,— Lautenberg said. “Kent Conrad is so responsible I can’t not listen to him when he presents something.—

One Democratic source close to the health care negotiations said Conrad’s plan has staying power because Republicans are still at the table on this idea, unlike the public plan, which they have rejected as a non-starter.

“It seems to be something that people are not dismissing out of hand, which for this health care debate is significant,— the source said. However, the source noted that the proposal needs to be explored more fully before anyone will know whether it is really the answer to finding a bipartisan solution.

The key, said one senior Senate Democratic aide, will be in level of involvement of the White House, which has been in daily contact with key players in Congress but has not offered its support or opposition to many of the proposals floating around.

“Here’s the dirty little secret in all of this — whether it’s the co-op [plan] or how you pay for it, I don’t think [President Barack Obama] wants to be responsible for anything Congress does,— the aide said. “That’s so he can come in to fix it later.—

But the aide said Obama would have to be more involved when Senate leaders try to marry the Finance and HELP bills —a job that could be tricky if Finance chooses to put the co-op plan in their bill. HELP’s bill includes a public insurance plan.

“It’s going to need a lot of White House participation,— the aide said.