I have maintained that conservatives will vote for McCain in the end, despite all their grousing now. My argument has been on a superficial political level: Democrat smears and October Surprises will anger Republicans so much that they will be driven to the ballot box to punish the Dems for their injustice. I came to this from introspecting over the last four or five elections and noticing what most motivated me to vote against the Democrats.
There is a deeper philosophical reason.
Have you noticed that only Objectivists are bothered by McCain's often repeated statement about sacrificing for something greater than self-interest? In their lists of grievances against McCain -- which include McCain-Kennedy, McCain-Feingold, McCain-Lieberman, opposition to tax cuts and his love of being a "maverick" -- conservatives never mention McCain's explicit altruism.
Obviously, they don't object because they share McCain's morality. Only Objectivists hold that rational self-interest is a virtue. Only Ayn Rand's radical philosophy challenges the traditional morality of altruism. Only Objectivists see a red flag when a politician exhorts people to sacrifice to the collective, for that way lies statism and dictatorship. Thomas Jefferson was remarkably astute when he included the right to life, liberty and the pursuit of happiness in the Declaration of Independence; writing before Kant, Hegel and their long tradition, he included nothing about sacrificing to the state or the collective.
Whenever there is a conflict between ethics and politics, people go with their morality. Ethics is more fundamental than politics. A man's politics depend on his ethics. If he believes in the morality of self-interest, then he will want freedom and capitalism. If he believes in altruism, then he will want state intervention in the economy. If he is consistent enough, he might even share John McCain's dream of using the state to orchestrate an orgy of collective sacrifice for something greater than self-interest.
In the end, conservative lip service to capitalism and freedom will be undermined, as it always is, by the conservatives' altruist ethics. They might disagree with McCain's politics, but they have no answer to his ideals. The tragedy is that McCain's ideals are pure poison.