With momentum for climate change legislation collapsing, Sens. John Kerry (D-Mass.) and Joe Lieberman (ID-Conn.) today are making what could be their last-ditch effort to regain their footing in time for floor action on a bill this year.

Facing a cramped election year schedule, Senate Majority Leader Harry Reid (D-Nev.) has essentially told Kerry and Lieberman to introduce their bill now so Reid can gauge the support in the Democratic caucus for moving forward. The plan is to let the bill marinate for a few weeks and make a decision after Memorial Day on whether to proceed.

After canceling a bipartisan bill introduction two weeks ago when their lead GOP sponsor, South Carolina Sen. Lindsey Graham, pulled out of talks, Kerry and Lieberman are set to roll out their measure today — sans Graham.

However, Reid has sent mixed messages in recent days about what he envisions as the future of climate change legislation this year.

First, Reid suggested in an interview with the Spanish-language station Univision this week that he could more easily pass a smaller, targeted energy bill, “because I have a couple of Republicans who will help me out on that.” He added that he does not have any Republican support for the broader climate change bill being pushed by Kerry and Lieberman.

But on Tuesday, Reid indicated that he is planning to give the duo a shot at pulling their effort back from the brink.

[IMGCAP(1)]”What I intend to do after [they introduce it] is let this bill be seen by everyone that is interested in the subject, and I think the week that we get back after the Memorial Day recess … I’ll get all the chairmen together and take a look at what we need to do with energy for this year,” Reid told reporters.

One Senate Democratic source said it was unclear whether Reid was simply procrastinating on making a decision, trying to give Kerry and Lieberman a real shot at building consensus, or just waiting for their effort to die under its own weight. Another senior source said Reid appeared to be warming to the idea of moving a narrowly focused energy bill produced by the Energy and Natural Resources Committee last year. That measure was originally intended to be a major part of any broader climate change measure.

If Reid decided to move the smaller energy bill, he would have substantial support among Democratic moderates.

“I’ve always felt like, you know, we marked up a good bipartisan bill in the Energy Committee. It’s a good place to start, and I think we could do it,” said Arkansas Sen. Blanche Lincoln, who, like other vulnerable Democratic incumbents, may be looking to avoid hot-button issues in Washington as she battles for her political life in a tough election back home.

Reid’s hedging this week seemed to reflect the skepticism Kerry and Lieberman are facing in the Democratic caucus — much less the Republican caucus, which believes Democrats are merely seeking to score political points with the rest of their legislative agenda this year.

Democratic aides said their caucus is split into several camps: one that wants strict limits on carbon emissions and a robust cap-and-trade system, one that wants a softer approach to attract Republicans and one that doesn’t want to deal with the issue at all.

Sen. Tom Carper (D-Del.) said the disastrous oil spill in the Gulf of Mexico was complicating Kerry and Lieberman’s ability to find Democrats with the political desire to take on the complex issue this year, particularly since their measure is expected to propose increased domestic oil and natural gas drilling.

“I think the appetite was fairly strong until about two weeks ago,” Carper said. “And with the offshore oil and gas blowout, I think we’ve seen a number of folks in our caucus, particularly those who represent states along the East Coast, are increasingly nervous about a grand compromise that includes anything new at this time on oil and gas development.”

Sen. Mary Landrieu said Kerry and Lieberman’s efforts combined with the oil spill has “been terrible timing,” despite her general support for addressing the issue this year.

“I think the team [of Kerry and Lieberman] wants to continue to push forward, but it may be very difficult to do . … It’s been a setback with this uncontrolled flow in the Gulf,” the Louisiana Democrat said.

Even Kerry seemed uncertain of his chances of bringing a bill to the floor this year. “Harry Reid wants to do it. The president wants to do it. Whether we can or not, we’ll wait and see,” Kerry said Tuesday. He also noted, “you have to proceed forward. You start at some point. You begin to organize. You have to work.”

Though Graham supports the broad outlines of the bill, he said the insertion of immigration into the Senate’s legislative scheduled smacked of crass political posturing, and he believes those kinds of decisions will color every policy debate leading up to the elections.

“I think a lot of [Republicans] believe, after immigration was rolled out, the body is taking less than a serious road in terms of between now and November, because it’s become all politics now,” he said.

He added, “I don’t see this product being able to gain traction right now.”