Moderate Republicans in California, having watched their party become increasingly dominated by conservatives as it sunk deeper and deeper into minority status, had big hopes after Arnold Schwarzenegger was elected governor in 2003. A new leader had arrived, one who because of a lightning strike of political good luck did not have to subject himself to the ideological litmus test of a statewide Republican primary. Just maybe, they thought, he could lead them out of the political wilderness. Schwarzenegger, as they saw it, was their kind of Republican: supportive of abortion rights, receptive to gay-rights issues, tough-minded on taxes, sensitive...