Marco Rubio is, at this point, almost the antithesis of the Republican establishment.
This is what Rubio and his boosters would like people to think. As a lot of the commentary about Rubio shows, it seems to be working. He has continued to rely on his uncharacteristic role as Tea Party-aligned insurgent in 2010 to ward off attacks from potential conservative rivals, and he has amassed a large store of goodwill among movement activists and pundits that will shield him from backlashes against any “centrist” maneuvers he makes in the coming months and years. Rubio isn’t an anti-establishment, insurgent politician. It’s true that he has voted against things favored by his party leadership in recent months, but I suspect this is mostly a function of wanting to maintain his anti-Obama credentials rather than proof of anti-establishment sentiments. He knows very well how politically damaging it can be to be too closely identified with Obama. Had Crist not made that mistake, we probably wouldn’t be talking about Sen. Rubio today.
Prior to his Senate run, he was part of the state party establishment, and has made a point of identifying himself closely with members of the Senate, including McCain and Graham, who are supposed to represent a lot of what very conservative Republicans despise. Rubio has been successful so far in having things both ways. Despite having many of the flaws that made conservatives distrust McCain, Rubio has won over many conservative audiences by treating them with the respect McCain refused to show them. For that and other reasons, he often gets a pass on things that would render other Republican officeholders politically radioactive in their own party.
It’s true that most Republicans will be even more willing to tolerate a relative moderate candidate in the 2016 cycle than they were this time, but being perceived as the relative moderate often depends on the other candidates in the field. On paper, McCain wasn’t that much of a moderate compared to his rivals, but he was perceived that way and encouraged people to think of him as such. If Jeb Bush chooses not to run, Rubio would be his obvious replacement and would likely reap the benefits of Bush’s connections. None of that means that Rubio will be the next nominee or even that he should be considered the favorite at this point, but there are fewer obstacles between him and the nomination than Enten thinks*.
* Of course, Rubio could always implode while giving the response to the State of the Union address tonight.