For all the talk in Congress that a public insurance option will make or break health care reform this year, the other alternatives that Members are considering for the overhaul appear to be equally as divisive.

Centrist Democrats are increasingly interested in a “trigger— — originally floated by moderate GOP Sen. Olympia Snowe (Maine) — which would only allow for a public insurance option as a fallback if private insurers fail to lower costs.

But exactly how the trigger would function — in other words, which benchmarks would be used to determine whether a public insurance option was implemented — could prove to be a hornet’s nest.

“Here’s the difficulty of it: You can’t just say a trigger comes into effect if, for instance, health care costs don’t go down, because they might not be going down for a host of different reasons,— said Sen. Joe Lieberman (ID-Conn.), who caucuses with the Democrats and opposes the public insurance option. “If part of the concern is, to use the phrase, ‘Keeping the insurance companies honest,’ well, there are more direct ways to do that.—

President Barack Obama indicated in his address to a joint session of Congress last week that the public insurance option isn’t a deal-breaker for his health care agenda. Nor is the proposal a part of the policy mix in the Senate Finance Committee, where a gang of six bipartisan negotiators has settled instead on a proposal to create nonprofit, medical cooperatives.

Finance Chairman Max Baucus (D-Mont.) has flatly insisted there are not enough votes in the Senate to pass a bill containing a public insurance option, a contention shared by many of his colleagues on both sides of the aisle.

But the reform bills that cleared the Senate Health, Education, Labor and Pensions Committee and three House panels each contain a public insurance option, and liberals have not stopped their vigorous push for it.

[IMGCAP(1)]Sen. Chris Dodd (D-Conn.), who led the markup of the HELP bill and is a strong supporter of the public insurance option, acknowledged the challenge of devising a trigger mechanism that could win broad support from the Democratic Conference.

But he said it is far too premature to assume that a public insurance option would not be a part of the final Senate bill. And he declined to say whether he could support a trigger option, should Senate Democrats move in that direction.

“I want to hold up on that because I’m a strong advocate of the public option, so I haven’t [considered] any fallback positions,— Dodd said. “I think the public option still makes a tremendous amount of sense, particularly in areas of the country where there aren’t any options.—

In the House, Democrats remain in wait-and-see mode pending action by the Finance Committee. Meanwhile, the price tag of Obama’s plan and its cost to both the government and the taxpayers emerged last week as a major issue dividing the Democrats on both ends of Capitol Hill.

House Moderates have pressured leadership not to press ahead until Baucus’ panel produces a bill, complicating the search for consensus on remaining hot-button issues. Baucus is expected to unveil a measure this week, perhaps as early as today, with plans to send it to markup next week.

“The biggest determinant is what smoke we see from the Senate,— one Democratic leadership aide said. “That shapes the time line for all of this.—

But House Democrats are keeping up their internal debate, diving back into the most contentious issue of a public insurance option in a midday Caucus meeting dedicated to discussing the provision. Follow-up sessions this week will focus on seniors and small businesses.

House Democratic aides were skeptical that they would reach any breakthroughs. Even within the fiscally conservative Blue Dog Coalition, for example, there is little unanimity about how to proceed on the public insurance option, including whether the trigger provision should be pursued as a compromise with leadership and liberal lawmakers.

While some Blue Dogs embrace the proposal, many are against it, and those opposed have yet to rally around either a trigger approach or a co-op model.

And, while several liberals have signaled a willingness to negotiate on the public option, leaders of the Congressional Progressive Caucus are pushing for a sit-down with Obama this week to discuss it in the wake of the qualified support that he offered the proposal in his address to Congress.

“There are a lot of discussions, but not a lot of clarity,— one senior Democratic aide said.