As regular readers know, I believe many people wildly overestimate the president’s power in general and the power of presidential rhetoric in particular. Ezra Klein had a great piece on this in The New Yorker a while back, in which he made two points. One was that there’s very little evidence that presidential backing leads to passage of legislation or major shifts in public opinion. And the other is that the president’s rhetorical support is as likely to polarize an issue as it is to bring people together around it.

This last point was on my mind today when I read about The Washington Post’s new poll. It’s a fascinating look at which issues are sensitive to Obama’s involvement. They asked people about various issues, and then asked about those same issues accompanied by Obama’s support.

When it comes to a ban on assault weapons or ending the war in Afghanistan, Obama’s support increases public support. When it comes to a “path to citizenship” for undocumented workers, Obama’s support decreases public support — which is another way of saying that it polarizes the issue, sending Republicans away from it. And when it comes to climate change, Obama’s support has … virtually no effect at all.

Washington Post poll

What are we to make of this? The WaPo story doesn’t really speculate. So I shall fill the speculation gap.

The “path to citizenship” thing is easy, and roughly what I would expect. As an idea, it makes sense, and it’s been floated by and to Republicans a number of times. But the country is intensely polarized, so when Republicans find out it’s Obama’s idea, they recoil.

How about the assault-weapons ban and an end to the war in Afghanistan? These are harder to explain. My guess is that a certain slice of the populace fears that such positions are “weak” and are afraid to support them without the validation of a Strong Leader. But I’m curious to hear other theories.

And finally, what about climate change? That one’s easy: Everyone has already made up their minds. The issue is thoroughly, 100 percent polarized. The tribal lines are drawn, so nothing Obama says is going to have much effect.

This polarization on climate is a bad thing and probably the most serious impediment to federal action. I know lots of climate hawks think that Obama could lead some kind of national teach-in and change things, but this poll, to me, confirms that such hopes are forlorn. Obama is already a partisan player in a partisan drama. He speaks for “his side,” or at least that’s how conservatives see it.

To bring conservatives around on climate, you need conservatives, or at least cultural figures who are viewed as trusted and nonpartisan by conservatives, to carry the message. Obama can do many things, but he can’t do that.