David Roberts makes the case:

Clean energy isolates the Republican base from the broad mass of American opinion and, in particular, from swing-state independents. It’s a wedge issue and an electoral winner for Democrats if they can quit playing defense and go on the attack. The appropriate response to threats from the U.S. Chamber of Commerce is a well-administered ass kicking.

Ed Kilgore situates the argument in a broader context of Democratic unwillingness to sell its own agenda:

It’s true that some sub-issues in this area remain tough – there’s no question progressives have lost ground with the public on dealing with global climate change during the last few years, and will always have trouble with policy prescriptions that deliberately aim at raising energy prices. But while it’s always appropriate to emphasize or de-emphasize this or that issue on strategic or tactical grounds at some particular moment, there’s something fundamentally wrong about an ideology or a political party that is unwilling to offer its own distinctive "take" on subjects the public cares about. David’s right there is a progressive opportunity on "clean energy" that ought to be fully exploited. Even if he was wrong, though, it’s a terrible habit to shut down thinking and talking about major national challenges just because "the other side" seems to have an advantage.