Erik Kain attaches too much significance to Rubio’s recent criticism of Gingrich:

No plans to endorse, but this is still picking sides. Rubio would make a smart pick for Romney’s VP for numerous reasons. He’s more reliably conservative than Romney. He’s a good speaker, likable and eloquent. He’s young and good-looking. And he’s a minority who would appeal to that much-alienated Hispanic vote.

Rubio wouldn’t bring nearly as much to a Republican ticket as many people think, but that isn’t my main objection to this. Gingrich has been attacking Romney in Florida for being “anti-immigrant,” and Rubio has described those attacks as “inaccurate” and “inflammatory.” Rubio isn’t saying this to take Romney’s side, but to oppose the efforts of a Republican who is to Rubio’s left on immigration to portray a position that is very similar to Rubio’s as “anti-immigrant.” This is the obnoxious language that pro-amnesty Republicans use when they want to impute prejudice to their intra-party opponents. Rubio objects to it because he is more conservative than Gingrich on immigration, and he doesn’t want Floridians to start thinking of his position on immigration as “anti-immigrant.” Rubio is acting in his own political self-interest, and along the way he helps to build up his credibility with conservatives beyond Florida. Gingrich has since decided to pull the ad.

Rubio has also made an effort to pour cold water on the Gingrich meme that Romney is the Charlie Crist of the presidential race. It doesn’t matter that the comparison makes a certain amount of sense, or that Romney’s campaign is actually rife with former Crist advisers. Rubio’s disagreement here focuses on the difference in partisan loyalty between the two: Crist was an opportunist who left his party rather than accept defeat in the primary, while he sees Romney as a reliable team player. As Crist’s opponent in the Senate primary and the general election, Rubio could not have remained silent without appearing to give tacit approval to Gingrich’s Crist attack, which would once again put him in the position of appearing to help the more “centrist” candidate beat up on the relatively more conservative one.