I've been on the side of those who thought that Ted Cruz was a viable candidate for the Republican nomination in 2016. Not a likely winner, but very plausible.
I'm pretty sure that's done now.
I was willing to defend Cruz's chances despite his quickly-gained reputation within the Senate for excessively sharp elbows. I thought that Hill reputation was a relatively minor factor in overall party view of a contender.
But what's happened to him now goes well beyond Hill reputation. Moreover, the type of bad reputation has changed, and that should matter, too. Three things:
1. It's one thing to have a reputation as a loudmouth; it's quite another to have a reputation as a loser. That's what the shutdown fight has done to Cruz. Among true believers he'll be the one who was a leader in a fight that surely would have won if the squishes hadn't sold them out. But for most party actors, including many sympathetic to Tea Partyism, he's going to be the guy who ran up the wrong hill.
2. I can't remember if Grover Norquist had already publicly feuded with Ted Cruz before the shutdown fight, but he's certainly doing it now. That's not good. The more broadly Republican party actors dislike Cruz, and the more intensely they dislike him, the harder it would be for him to get the nomination. We saw the way this worked with Newt Gingrich in 2012: every time Newt stumbled, there were plenty of Republican opinion leaders ready to kick him while he was down. That's where Cruz is heading now.
3. Yeah, I think that the polling probably matters at this point. He's still fairly unknown, but I can't think of anyone who had established a 2-1 against ration on the favorable/unfavorable question eventually getting anywhere close to a major party nomination. Sure, it could still change, and I suppose one could argue that all it means is that the MSNBC audience has learned to dislike him...but then why hasn't the Fox audience learned to love him?
Add up all three of those, and at this point I think he's probably off the list of serious contenders. He still has the basics of a viable candidate (conventional credentials, if only just barely, and he's within the mainstream of his party on public policy positions). But I think it's extremely likely that he's in the process of being winnowed out.