Daniel Larison writing in the American Conservative notes:
What we know about Republican nomination politics tells us that Cruz is an extreme long-shot candidate. Republicans almost never nominate an insurgent candidate, and they certainly don’t choose to nominate the one with the least experienced in elected office when they have a large number of alternatives available. Many people are comparing Cruz now to Obama in 2007, and there are some similarities, but Cruz is even more of a novice in elected office than Obama was when he announced his candidacy and he doesn’t really have any major issue that he can use to propel his candidacy. There is no significant constituency that Cruz will be able to mobilize on his behalf, and there is no issue that he will be able to “own” to the detriment of his rivals.