It’s increasingly looking like House Republicans will eventually face a clear choice on immigration: bring up and pass the Senate bill, mostly with Democratic votes, or take the blame for killing comprehensive immigration reform.

That’s been the most likely outcome for some time, but the diverging paths of the House and Senate bipartisan efforts show that it is playing out exactly that way.

On the Senate side, the main theme of the markup of the bill in the Judiciary Committee has been that the bipartisan coalition has stuck together, meaning that the original bill has survived largely intact, with potentially divisive amendments from both sides defeated and deals on tough issues reached. The result is a real bipartisan bill that should emerge from committee this week and which may wind up winning the votes of most Democrats and many mainstream conservative Republicans.

On the House side … well, the best the House bipartisan group can do on key issues is to agree to disagree for now. Meanwhile, Democratic leaders have backed away from the House bipartisan effort because it is too conservative for them, while Republicans still haven’t committed to moving any full comprehensive bill — and with conservative outside groups adding to the pressure, the math of the House will require leaders of both parties to be on board for any House-authored bill to succeed.

In other words, it still appears that the only bill that could win in the House would be something passed by a strong bipartisan vote in the Senate.

As I’ve said before, then the key players will be mainstream House conservatives, who will have to decide who to offend: anti-immigrant voters in Republican primaries, or Latino and other voters who want reform. Many of those conservatives will vote against the Senate bill if John Boehner brings it up, but he won’t do that without their (private) support.

Greg wrote earlier today about one of the remaining tough issues for Democrats, the choice of whether to concede to Republicans on immigration issues facing gay and lesbian couples. That’s a good demonstration of how legislating — real legislating, in a real law-writing representative chamber — forces all kinds of painful choices. The bottom line here is that House Republicans remain absolutely incapable of doing real legislating in most cases, which reduces their ability to influence the content of legislation. All they really can do is approve or disapprove. They certainly will have to make a choice on that, but only the upper chamber is doing the real legislative work.