There is a price for making everyone you come into contact with think you're an asshole and a jerk. Back in 2008, Republican and Democratic Senators came together to pass a sense of the Senate resolution affirming that John McCain was a natural born citizen. Claire McCaskill says today that she won't be doing any similar favors for purported American Ted Cruz. But it's not just a Democrat. The silence of Senate Republicans is positively deafening. Mitch McConnell also says he's not getting involved. Jeb Bush and Mitt Romney have both tried to put the kibosh on the growing Cruz-birther movement. But in the Senate, where people know Ted Cruz, virtually no one is coming to his aid. McCain himself is suggesting he's at least Cruz-birther-curious if not coming out as a full-blown Cruz birther.
Whatever else you may think of him, John McCain is well liked in the Senate. Not Mr. Congeniality - but still well-liked and respected. Meanwhile, Cruz is perhaps more disliked than any of the other 99 individuals currently serving in the Senate. Think about that. That's something! And it matters. In the non-impossible scenario that Cruz becomes the nominee, yes, everyone will endorse him. Most will campaign for him. But that level of antipathy is quite difficult to overcome. And it will matter: at best sand in the gears of his campaign and possibly the source of much greater disruption.