The latest YouGov/Economist survey of Republican voters included the remarkable finding that Trump and Carson are perceived to be more capable of winning the general election than any other candidates by a significant margin:
I have no idea where this confidence in Trump and Carson’s electability comes from, since they are two of the only candidates that have never been elected to anything. Even so, this helps to explain why half of the Republican primary electorate backs these two over all of the others. It is often taken for granted that the more “establishment” candidates are more electable and are perceived as such, but as several polls have found the second part isn’t always the case. The belief that these candidates “could possibly win” may also be related to how favorably they are viewed, at least as far as Carson and Rubio are concerned. Because most Republicans like those two, they are perceived as capable of winning the general election on the unproven assumption that non-Republicans will like them as well. Why Trump is perceived to be capable of winning a general election is harder to explain, and I don’t have a good answer for that one.
Trump and Carson have been expected to lose support over time as it became clear that they weren’t “serious” candidates, but this hasn’t happened. Insofar as Trump has lost ground in some places, Carson has been the one to gain, and both of them together are taking a larger share of the Republican vote than they were earlier in the race. The candidates that have faded under pressure over the last six months have been the “credible” and “plausible” ones. Trump and Carson are almost certainly among the least electable candidates for the general election, but perhaps because they have been dominating the Republican contest thus far Republican voters believe otherwise.