Bank on this. When President Obama rolls out his new regulations on existing power plants in coming weeks, the roar of gloating from Republicans will be deafening: It’s an absolute political disaster for red state Democrats! Commentators will concern troll about how awful this is for these Dems, and reporters will track every twist and turn in their statements for signs of adherence to or distance from the proposed rules, all of which will be hyped in the most negative way possible.

Dem strategists involved in contested Senate races tell me they’ve already begun to think through how to respond to the coming political storm. They do concede vulnerable Dems will have to deal with the new rules – the issue has enormous and far reaching consequences – and they expect Dems to distance themselves. But they also say the hype will be out of sync with political reality, and that in the end, this just won’t matter that much.

“They’ll have to talk about this and figure out their position on it and face questions about it,” a Democratic operative who’s advising candidates in red state races tells me. “But will it be something that changes the dynamic of the races? I don’t think so. This will very much be a story that’s written over and over again when it happens, but 90 percent of the narrative will be wrong.”

The most obvious races where the rollout of the new Environmental Protection Agency rules will matter are in states like Kentucky and Louisiana, where battles are already underway over energy. Mitch McConnell hits Alison Lundergan Grimes regularly as an agent of Obama’s war on coal, and Republicans are using the Keystone delay to cast doubt on Mary Landrieu’s claim that as chair of the Senate Energy Committee she’s well positioned to deliver for Louisiana.

But Dems fully expect this issue to resonate in tough races that aren’t necessarily focused on battles over energy. Republicans will seize on the new EPA rules to bolster their broader case that Obama big government is smothering the economy, and that the only way to ease people’s economic misery is to elect Republicans to the Senate to roll it back.

Along these lines, Dem strategists point out that Dems are already dealing with a similar dynamic. Grimes and Landrieu are already fending off efforts to tie them to Obama’s energy policies and more. In other races, Dems like Kay Hagan and Mark Pryor are already pushing back on efforts to tie them to the ultimate symbol of Obummer Big Gummint, i.e., Obamacare. Dem strategists believe the EPA regs will be politically dicey, but – just as in the case of Obamacare — will also provide another occasion for red state Dems to prove their independence of national Dems. That, of course, has pluses and minuses: It achieves distance from Obama, but also reminds red state voters why they don’t like Democrats.

“It’s an opportunity to say, ‘I disagree with the president, and he’s wrong,’” a Dem strategist advising Senators in competitive races says. “I’m not sure at the end of the day whether people in those states are likely to say, ‘this shows Democrats are trying to screw us,’ or, ‘I’m glad my Democrat is standing up for me, and he will do other valuable things.’ Where this really nets out is hard to know. But we’ve been dealing with the basic thematics here for a long time.”

Of course, one could argue that perhaps even vulnerable Dems should consider supporting the EPA regs on the merits. And on the politics, the League of Conservation Voters recently commissioned polling that showed voters overwhelmingly trust the EPA over Congress (which remains woefully unpopular) to set regulations on carbon pollution. But the politics of this, unfortunately, might not turn on the details, since Republicans will be using the EPA regs to make a broader case about government and the economy, at a time when economic anxiety is widespread, in regions where Obama is very unpopular. As Jonathan Chait puts it:

Republicans are likely to have the better of the debate politically. Support for regulating carbon emissions may be broad, but it’s tissue-thin…regulating carbon emissions creates almost no winners. There will be no equivalent of the millions of people newly granted access to medical care, no heartwarming stories of long-suffering patients seeing a doctor for the first time in years. Climate regulation doesn’t create a benefit. It doesn’t even prevent a loss. Its only goal is to mitigate the extent of the damage.

And this is why, unlike carefully selected election-year issues like the minimum wage or equal pay, Obama is not picking this issue to help his party save Senate seats. He is doing this because, given the enormity of the stakes for centuries to come, there is no morally defensible alternative.    

The very fact that this will be accomplished through executive action, of course, liberates Senate Dems from having to support it. It remains unclear how exactly they’ll respond, but one thing that seems certain is that the D.C. chatterers will overplay its political importance, while the policy significance of it will suffer the opposite fate.

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.