Congress is in session this week and it's not likely that any energy legislation will come up, much less pass. But there's still important maneuvering afoot: Namely, a number of Republicans and conservative Democrats may try to block the EPA from regulating greenhouse-gas emissions on its own:

Sources on and off Capitol Hill are expecting the Senate Appropriations Committee to vote on an amendment to undercut Environmental Protection Agency climate change regulations when it marks up the agency’s annual spending bill. Such an amendment has a serious chance of passing given widespread backing on the issue from Republicans and moderate Democrats – so much so that environmentalists were asking committee leaders to punt on the markup entirely.

Alaska Republican Lisa Murkowski used to be the person in charge of trying to stop the EPA, but she's been distracted of late after her primary defeat. Still, Politico reports that there are plenty of Democrats willing to take her place: Byron Dorgan, Ben Nelson, Mary Landrieu. For their part, White House officials have said Obama would veto any bill that kneecapped the EPA's ability to regulate carbon emissions—but how much of a showdown do they want?

On the policy side: Here's a primer as to what EPA carbon regulations would look like. They probably wouldn't be as effective as a congressional climate bill, but they could still achieve quite a bit. And, for now, the EPA is the only force in the country (apart from a few liberal states) that can do anything to mitigate climate change. If Congress manages to block the EPA this year—and Republicans next year just let to issue fester—then the federal government won't be doing a thing about global warming for a long, long time. And if California voters approve a referendum this fall to block the state's climate law, things will look really bleak…