I believe this is why the GOP produces such poor candidates in the last 20 years or so; they must pander to the hard core of the party to become a candidate, and the people that pass that test are almost always too far removed from the electorate to win the general.

This is also why we're devolving to a system of ruling families. Clinton was never the best candidate. She was the presumed candidate and the candidate preferred by the party core, so nobody was willing to challenge - except Sanders who could seriously run on ideology.