Jonathan Bernstein notes the weakness of Jeb Bush’s candidacy so far:

If Bush (or anyone else) was decisively pulling ahead, some marginal candidates would be dropping out. For that matter, Florida Senator Marco Rubio would probably have decided not to run. No sign of that.

It is remarkable how many other Republicans have been willing to signal that they intend to run in the months following Bush’s decision to “explore” a presidential bid. Most observers expected that the 2016 field would be larger and more competitive than usual, but it is a bit surprising that Bush’s entry into the race seems to have had no effect on the calculations of the other candidates. Instead of clearing the field or discouraging challengers as his brother’s candidacy did sixteen years ago, Jeb Bush’s candidacy seems to have been underwhelming enough to give his many challengers no pause at all in preparing their own campaigns. Rubio’s candidacy still doesn’t make any sense for many reasons, but it is telling that Bush’s bid didn’t keep Rubio from preparing his own. I still assume Rubio’s campaign will go nowhere, but it is a reflection of how unimpressed Bush’s rivals are by his candidacy that Rubio would choose to pursue a presidential campaign instead of his own re-election bid.

Bernstein continues:

If party actors remain split or uncommitted and prefer to wait for tests of electoral strength, it’s easy to imagine Bush finishing fifth or lower in Iowa, failing to rally in New Hampshire, and then finding himself almost a non-factor in South Carolina. One thing’s for sure: Waiting for the Florida primary to come around isn’t going to be a successful nomination strategy.

That’s a possibility. It’s not entirely fair to liken Bush to Giuliani. Giuliani’s “wait until Florida” plan was transparently desperate and absurd. Bush has at least some qualifications to be president. Even so, Bush could have some similar difficulties in the early states. The early evidence suggests that his support is not nearly this weak in New Hampshire or South Carolina. Jeb Bush seems to be somewhere between being another Giuliani and another McCain. He may not be able to eke out a nomination win as McCain did, but he isn’t going to be thoroughly humiliated and forced to drop out early on. It’s certainly true, as E.J. Dionne observes, that the more conservative candidates there are in the race the better Bush’s chances are. There are going to be so many of these candidates running this year that the perceived weakness of Bush’s candidacy could help keep him afloat.