Polling data suggests that President Obama’s executive action on immigration has hardened Republican opposition to a path to citizenship. Kevin Drum, noting that “it sure seems as if Obama polarizes more than any previous president,” wants better data on the question:

In any case, this would be an interesting project for someone with access to high-quality polling data that reaches back over several decades. Is the partisan response to President Obama’s proposals more pronounced than it was for previous presidents? If so, is it a little more pronounced, or a lot? Someone needs to get on this.

I agree that there’s an interesting empirical question here, and if it is the case that Obama is more polarizing than his predecessors—as some research suggests—the reasons may well include those that Drum posits, like the radicalization of the GOP and the growing ideological homogenization of each party.

Yet the empirical question is not the only issue, and research into the causes of polarization might end up revealing that we need a better vocabulary for discussing this topic. Consider two simplified paths by which voters might come to their opinions: First, they might decide by carefully considering rival positions and weighing competing priorities. (This is a simplification, and obviously an optimistic one.) At the other extreme, they might make decisions by using political figures as signals: If Obama is for it, I’m against it.

It’s that latter dynamic which seems to be happening with immigration. And in this case, the opinion-by-signaling is especially detached from policy realities, since nothing in Obama’s executive action grants undocumented immigrants a path to citizenship. Republican voters have changed their minds on a different policy issue, in all likelihood due to the mistaken impression that Obama acted to unilaterally settle it. If you like the idea of living in a democracy governed by well-considered opinions, this is disheartening, to say the least.

It also indicates why, in some cases, it could be misleading to say “Barack Obama is a polarizing president,” insofar as that statement suggests that Obama himself is responsible for polarizing public opinion. The culprit may instead be confusion among Republicans who think Obama has unilaterally created a path to citizenship for millions of undocumented immigrants. Among all Americans, support for a path to citizenship has recently tumbled below 50 percent. But as The Washington Post reports, that shift “is almost completely among Republicans,” who favored citizenship over deportation just over a year ago. Those numbers have dramatically reversed in the last 12 months, and if the reversal is due to anger over Obama’s steps on “citizenship,” then it’s just factually mistaken. Voters may well have the President in mind when they change their views on these questions, but that doesn’t mean it’s always accurate to say that the President has split the electorate. A slightly more precise vocabulary would help us avoid misplacing the blame for our polarized politics.