A rational player concedes to a known crazy type in a negotiation. If the crazy type is committed to a tough strategy, meeting that strategy with toughness leads to disaster. Hence, a rational opponent will concede. But this means a rational type has the incentive to pretend to be crazy. Then, a rational opponent will still concede as crazy and rational types pool.
This strategy might be effective in a two player game with one-sided incomplete information. But if one side is the Republicans in the Senate, it is not going to work because the McCain, Ayotte, Collins… part is too rational to send the country over the debt limit. So what to do?
One strategy is to compromise and try to win the Presidency. This is the establishment strategy with all its prescriptions of outreach to women and immigrants. But only a centrist appeals to the wishy-washy median voter. So if you are Ted Cruz, you cannot get the policies you want via a centrist Republican winning the Presidency.
The other strategy is to make commitment credible. This involves primarying those who do not vote crazy. Partisans turn out in droves in primaries and even a rational politician who wants re-election is forced to act/vote crazy to get into office. Then you have enough crazies or acting crazies to filibuster if your demands are not met. In essence, you give up on winning the Presidency and focus on ruling in opposition as a minority.