A lot of the news around Jeb Bush of late has concerned his potential hurdles and the skepticism he supposedly inspires among the Republican base. So we get articles with titles like "In Iowa, Jeb Bush Risks Support With Unpopular Stances" and "NBC News Poll: Republicans Are Divided Over Jeb Bush Candidacy," which are true for the moment, but Jeb has far less cause for concern than it might appear.
Let's start with Iowa. Jeb Bush is probably not going to win the Iowa caucus, because Iowa Republicans are not only not like other Americans, they aren't even like other Republicans. Which is OK for Jeb, because all he has to do is lose respectably there, after which it'll be on to the much friendlier ground of New Hampshire. Just like Mitt Romney did in 2012 and John McCain did in 2008. We tend to forget, in all the attention Iowa gets, that winning there has little if any relationship to getting the nomination.
Second, it's true that many Republicans are looking askance at Jeb now; in that NBC poll, 49 percent said they could see themselves voting for him, while 42 percent said they couldn't. Those aren't good numbers, but when Republicans get asked a question like that today, they're comparing their imaginary perfect candidate with Jeb-whom they don't really know all that well, but do know is another Bush (i.e. old news) and do know has some less conservative positions on a couple of issues. When only 17 percent say they couldn't see themselves voting for Scott Walker (compared to 53 percent who could) it's largely because while they don't know much about Walker, they haven't heard anything they didn't like. So as far as they're concerned, he might turn out to be that fantasy candidate.
As the race goes on, the field will begin to winnow down, and the answers to that question will get more concrete. When there are only, say, six candidates still running and only two that get any discussion in the press, voters will be focused on a choice, which isn't how they're focused now. And they haven't even begun to get into the electability argument, which inevitably plays a role in every presidential primary.
By the time you get to the late stages of that process, what seemed like deal-breakers back in March 2015 don't seem so important anymore. Voters become willing to compromise. As I've argued before, they're ideological satisficers: They don't need the perfect candidate, they just need a candidate who's good enough.
I'm not saying Jeb Bush is guaranteed to get the nomination; it's way too early to make that prediction. But a lot of Republicans who are turning their noses up at him now will probably be perfectly fine with him a year from now.