But Mr. Romney is seeking the Republican presidential nomination, and whatever his personal beliefs may really be — if, indeed, he believes anything other than that he should be president — he needs to win over primary voters who really are severely conservative in both his intended and unintended senses.

So he can’t run on his record in office. Nor was he trying very hard to run on his business career even before people began asking hard (and appropriate) questions about the nature of that career.

Instead, his stump speeches rely almost entirely on fantasies and fabrications designed to appeal to the delusions of the conservative base. No, President Obama isn’t someone who “began his presidency by apologizing for America,” as Mr. Romney declared, yet again, a week ago. But this “Four-Pinocchio Falsehood,” as the Washington Post Fact Checker puts it, is at the heart of the Romney campaign.

How did American conservatism end up so detached from, indeed at odds with, facts and rationality? For it was not always thus. After all, that health reform Mr. Romney wants us to forget followed a blueprint originally laid out at the Heritage Foundation!

My short answer is that the long-running con game of economic conservatives and the wealthy supporters they serve finally went bad. For decades the G.O.P. has won elections by appealing to social and racial divisions, only to turn after each victory to deregulation and tax cuts for the wealthy — a process that reached its epitome when George W. Bush won re-election by posing as America’s defender against gay married terrorists, then announced that he had a mandate to privatize Social Security.

Over time, however, this strategy created a base that really believed in all the hokum — and now the party elite has lost control.

The point is that today’s dismal G.O.P. field — is there anyone who doesn’t consider it dismal? — is no accident. Economic conservatives played a cynical game, and now they’re facing the blowback, a party that suffers from “severe” conservatism in the worst way. And the malady may take many years to cure.