The popular rant on internet political forums is that a more conservative candidate will win, whereas a mainstream candidate will not.
Reagan won just 50.8% in 1980, coming after disastrous Carter. But Reagan was a household name, a trusted figure, a mainstream personality.
Goldwater won 38.5% in 1964 without a 3rd party. That ought to be allowed to sink in.
In current polling, the more mainstream GOP prospects outpoll the more conservative ones.
The notion, if only the GOP would run Ted Cruz or Michelle Bachmann, all the reclusive "true conservatives" will get out and vote in massive numbers, is ludicrous.