ANOTHER HEAD COUNT OF HOUSE EXTREMISTS & THEIR FELLOW TRAVELERS

Byron York wrote that there are 30 GOP extremists in the House and another 20-30 who will side with them because they are afraid of a primary challenge.  Robert Costa of the NRO has a different estimate: 30-40 extremists and 50-60 who want to avoid a primary.  I think Costa also got to the real cause:

The outside groups don't always move votes directly but they create an atmosphere of fear among the members. And so many of these members now live in the conservative world of talk radio and tea party conventions and Fox News invitations. And so the conservative strategy of the moment, no matter how unrealistic it might be, catches fire. The members begin to believe they can achieve things in divided government that most objective observers would believe is impossible. Leaders are dealing with these expectations that wouldn't exist in a normal environment.