If Obama wins the nomination, something that is becoming increasingly likely as the Cult of Obama spreads through the ranks of liberals, then there's no way to campaign for Hillary against McCain, making it a non-issue.
I certainly didn't campaign for McCain in the primary, but all is not lost. While we may have failed to elect the 'best' candidate, the Democrats do not present any alternative. To say that there's no difference between McCain or Hillary or Obama is absurd and ignorant. While I usually like Ann Coulter and Rush, they've made some very poor statements these past few weeks.
McCain is in favor of conservative judges... and EVEN if he said Alito was too conservative, I'd rather see six more Roberts on the court instead of a half dozen ACLU attorneys.
Fact of the matter is that right now, the damage a true liberal President, with the Democrat controlled congress, can do in just ONE TERM is too great. You simply CAN NOT roll back the government programs fast enough. Not to mention the global treaties they'll sign. Or the wave of vote buying social programs the Democrats will pass to ensure their support for the 21st century as they had in the 20th. And to presume that the public will reject the congress, without some tragedy befalling the country, is overly optimistic.
You can't let the perfect be the enemy of the good. Politics IS NOT pure, nor has it ever been. If you go back to the founding of this country, you'll find that more often than not, it's the result of compromise. The constitution itself was the cause of HUGE debates and fighting between the Federalist and the poorly named "Anti-federalist" who lost but so often were so right. (they were more federalist then the federalists who claimed the name first)....
McCain isn't a pacifist. He doesn't believe in huge deficits. He does have some core conservative values. And ultimately, these things have to outweighs his failings. And it's undeniable he's preferable to the Democrat option, as most Americans will likely realize (so long as they aren't put under a spell by Obama.)