The biggest data point that suggests Republicans are more receptive to some kind of immigration amnesty? Rubio is a possible candidate for the presidential nomination in 2016. None of his likely primary opponents denounced him.
Antle may be right about this, but I suspect that this is not the right way to measure Republican opposition to the proposal. Republicans have supported nominees that were more or less pro-amnesty in three of the last four presidential elections, and they have done so in spite of the nominees’ views on immigration. It was Romney’s opportunistic embrace of a different position that stands out as the exception in recent Republican presidential politics, so we should expect Rubio to endorse something more like a Bush-McCain view on the subject. As Jeb Bush’s protege, there was never much chance that Rubio would end up adopting any other view. None of Rubio’s likely opponents has denounced him over this so far, but then none of them needs to do that yet. We probably won’t see this kind of direct attack on Rubio until the primary candidates begin debating one another.
McCain’s immigration record was especially damaging for him in 2007 because he and his allies in the Senate argued for their preferred legislation in the most strident, offensive way possible. Even if the immigration bill in 2007 hadn’t been a worst-of-both-worlds compromise, the contempt that its supporters showed for their opponents still would have stirred up strong resistance. Rubio is presumably smart enough not to make the exact same mistakes that McCain, Graham, et al. made a few years ago, and as Antle notes he has a reservoir of conservative goodwill to draw on that McCain never had. But it might not matter for his future political ambitions.
As we all know, McCain was able to overcome the ill-will his immigration rhetoric generated, and he became the presidential nominee despite being deeply distrusted loathed by movement conservatives. McCain’s example suggests that there are enough moderate and “somewhat” conservative voters in the early primary states to allow pro-amnesty candidates to secure the nomination on a fairly regular basis. Immigration isn’t likely to be the issue that derails Rubio, but I wouldn’t assume that a lack of criticism directed at Rubio implies that Republican opposition to amnesty has decreased significantly.