Here’s something to keep an eye out for: Republicans who favor immigration reform carefully laying the groundwork to blame someone other than themselves — unions, Obama, etc. — if the heat from the right gets too intense and forces Republican officials to bail on reaching a reform compromise.

Buzzfeed and Politico both report that Republicans are criticizing unions for insisting on various worker protections as part of the guest worker program that is expected to be a key part of of any immigration reform compromise. Business groups and Republicans are claiming that unions are asking for too much and are on the verge of killing the whole effort. “I don’t think it’s any secret that in the past, unions killed immigration reform,” says Marco Rubio, referencing disagreements over the failed reform effort in 2007 (which actually was primarily killed by conservative Republican opposition).

I”m not buying it. My guess is that what’s really going on here is that Republicans need to be able to say they were not to blame if the right ultimately doesn’t allow them to reach a deal with Democrats on the real core issue — the path to citizenship.

This isn’t to say there aren’t genuine sticking points over the guest worker program. There are. As Buzzfeed documents, there are a range of proposals demanded by labor that some Republicans — particularly in the House — may balk at, such as an annual cap on low wage work visas; barring work visas for much of the construction industry, and a trigger that would only allow work visas once unemployment here fell below a certain level. Another sticking point is that the AFL-CIO and other unions want assurances that employers who bring workers in through the program will have to pay above median salary for the industry.

But the big picture here is what really matters. And the big picture is this: Congressional Republicans know they are going to have to embrace comprehensive immigration reform, including a path to citizenship, if they are going to blunt the destructive impact that ongoing demographic shifts are already having on the party. All the other sticking points are essentially sideshows. The main question that is central to the hopes of any deal is whether Republicans will be able to cross the path-to-citizenship Rubicon.

This isn’t the first time something like this has happened. Back in February, a White House immigration plan that would provide a faster path to citizenship than Republicans want leaked to the press, prompting Republicans to angrily question Obama’s motives, while claiming that he risked killing hopes for any reform. But that became less tenable after pro-reform Senators John McCain and Lindsey Graham met with Obama and declared that they thought he sincerely understood GOP needs in the talks.

Meanwhile, anti-reform politicians are trying to instill fear in Republican officials who are willing to cross that path-to-citizenship Rubicon. GOP Rep. Steve King yesterday warned that Republicans who embrace citizenship are on notice: “I think there’s going to be a constituent backlash against this thing soon, as they see it moving in that direction.”

Labor officials I spoke with today don’t even believe that there’s any real chance the whole deal will collapse, no matter how much the right rages. They believe Republicans know they must embrace citizenship to ensure the party’s survival, and are making noise about unions threatening the deal in order to win more concessions.

Whether or not that’s true, it seems overwhelmingly obvious that the only question that really matters is whether Republicans will ultimately be able to accept citizenship. If they can, it seems clear that other peripheral issues will get resolved.

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.