It's because there's not much downside to voting 'no.'
The topline numbers in all these immigration reform polls are striking -- just as they were during the gun debate, when 90 percent of Americans supported increased background checks. But those topline numbers don't really tell the story.
Case in point is a new Quinnipiac poll.
The poll shows 54 percent of Americans support a path to citizenship, while 29 percent favor deporting illegal immigrants. (Other polls, we should note, have shown even stronger support for a path to citizenship.)
Yet, when it comes to how Congressional members' votes would actually affect their chances of reelection, it's a total wash. About a quarter of those polled (26 percent) say they are more likely to support a member if he or she supports a path to citizenship, and about a quarter (24 percent) say they are less likely to support him or her.
The numbers closely match those from this month's Washington Post-ABC News poll, which showed 58 percent supported a path to citizenship. When it boiled down to it, though, just 23 percent said they supported a path to citizenship and could not vote for someone who opposed it, and 24 percent said they opposed a path and could not vote for someone who supported it.
In other words, there's not much to be lost -- individually and in the near term, at least -- for congressional Republicans who oppose immigration reform, even as a strong majority of Americans support that goal. It's the same phenomenon we saw with gun control, where opponents were much more adamant -- and punitive -- than proponents.
And if you dig a little deeper, you'll find there's plenty for Republicans to lose by supporting a path to citizenship.
According to the Post-ABC poll, 37 percent of Republicans say voting for a path to citizenship is a deal-breaker for them, while 12 percent say voting against it is a deal-breaker.
The Q poll, similarly, shows that 36 percent of Republicans would be less likely to support someone who votes for a path to citizenship, while 15 percent would be more likely.
In other words, for Republicans whose districts are so red that they only have to worry about their primaries -- which is about two-thirds or three-fourths of House Republicans -- it seems clear that voting against immigration reform is actually the more politically expedient path.
Now, none of this addresses the real reason Republicans feel the need to pass immigration reform -- the party's long-term appeal to Hispanic voters. And there will be some GOP members who feel strongly that they need to pass immigration reform for that and other reasons.
But politicians are always leery of taking votes that could cost them a reelection, and it's often much easier to vote 'no.'
In the end, it's quite possible that a vast majority of House Republicans will arrive at that calculation. And it could very well be the reason that immigration reform fails -- just as gun control did.
Scott Clement contribute to this post.