I have been somewhat skeptical of the notion that the Senate overwhelmingly passing a comprehensive immigration reform bill – 70 votes in favor seems to be the benchmark here – will, in and of itself, force the House to accept a pathway to citizenship or otherwise palpably move the House's conservative majority. I thought the juxtaposition of a strong bipartisan Senate majority running up against a very partisan House might strengthen reform advocates at the margin (especially those concerned about the party's image), but I also tend to view arguments revolving around legislative momentum as being overhyped in the same way that the bully pulpit and the "Green Lantern" theory of presidential leadership – that Republican intransigence owes to a failure of will on President Obama's part – tend to be wildly overdrawn.
But I thought running up the score in the Senate was, on balance, a good thing. Ezra Klein makes a couple of fairly compelling arguments today, however, that a big Senate win could backfire.
The Senate typically jams the House by passing legislation with 60 votes and then arguing the compromise is so delicate that it can't be substantially modified. In this case, the House could plausibly argue that the Senate has at least 10 votes to spare (and 19 if there's no viable filibuster) and so can afford to move towards the House in conference.
It could backfire in another way, too. Everyone in the House agrees that the House bill will have to be measurably to the right of the Senate bill. So every reasonable (or at least non-deal killing) compromise the Senate makes to get 70 votes is one fewer non-deal killing compromise the House can make to show they've pulled the Senate bill to the right. And if there are no big non-deal killing compromises available to them, that doesn't mean they'll simply pass the Senate bill unchanged. It means they'll start in on revisions that will kill the deal.
It's a reminder that focusing too much on the big headline (70 votes!) can cause you to lose sight of the finer points that can make the difference between passing a bill and wondering where everything went wrong.