Why the possibility of Trump becoming the Republican nominee is a terrible thing
economist.com
economist.com
However, the early caucuses, primaries, and influential straw polls are mostly in places that favor the most extreme right candidates. The kind of candidate that can appeal to the middle of the road GOP voter, and the moderates, and the independents, and so actually have a chance doesn't do well in those early contests.
If a candidate who has not been extreme right before takes a turn in that direction to do well in those early contests they lose the moderates and independents, and although they might get enough far right support from that to make it through those early contests they don't really gain the far right's trust.