Immigration reform advocates are fond of citing broad support for their cause. But in fact the coalition behind the Senate Gang of Eight comprehensive reform bill is fragile and loosely cobbled together. How could Big Labor and the Chamber of Commerce and the tech world and Big Agriculture all unite behind one bill? Very tentatively.

It wouldn’t take much to break the coalition apart. And if that happens, the effort to enact comprehensive immigration reform could blow up, not just for the moment, but for some time to come. And there are signs that is exactly what is occurring now.