The Bush presidency, then, was both a failure and a fraud. Instead of foreign policy restraint and modest conservative governance, the Bush administration delivered a pair of endless deficit-financed wars, cynical posturing over social issues, soaring federal spending and, eventually, a large-scale emergency intervention in the economy.

Arguably as important as the particular failures themselves, however, was the way the party infrastructure — its leaders and functionaries, its activists and operators — formed a partisan phalanx around the president, playing down his flaws, if not refusing to acknowledge them.

There is always some space between a party’s voters and its leaders, some difference between what the average supporter wants and what the elected representatives are willing to do. But by excusing Mr. Bush’s errors, Republicans radically expanded the trust deficit, creating a yawing gap between the party’s base and its elites, one that has persisted, and grown, in the years since.