I have said it about a million times. The republicans and the conservatives are essentially two different parties that are trying to share the same house. I guess I could look up the history of the wig party to see if there was ever a greater need for a party to split apart, but I don't think there is. the conservative base is not going to turn out for Christie and the Moderate base is not going to turn out for Cruz. You try to figure that out into a win for the R's. McCain and Romney were hamstrung by the same phenomena. It is hard enough to win an election without your own party holding you back.
The way congressional districts are formed is completely corrupt for either party. I am not suggesting that democrats don't partake also, but I am asserting that if it were not the case so many "extremist" would not be able to win elections. To prove my point I will remind everyone that despite single digit approval ratings 85% of incumbents are going to stay in office this next election. It is not a tie score establishment party politics is winning vs. us and it is not a close competition. Stop thinking in terms of party politics and you will see that we only have the illusion of choice in our congressional leadership.