The conservatives give specific reasons why they dislike John McCain - campaign finance, immigration and voting against tax cuts, but the real reason, McCain's ultimate sin is that he has never acknowledged their relevance or recognized their power. Last year he didn't even attend their CPAC love fest and although he did everything he could to prove he was just as crazy as they are this year he really didn't acknowledge or recognize them.
David Brooks explained this a few weeks ago when he discussed the conservative support for serial flip flopper Mitt Romney:
The leaders of the Republican coalition know Romney will lose. But some would rather remain in control of a party that loses than lose control of a party that wins.
A McCain win in November would prove that the conservatives who have run both the country and the Republican party into the ground are indeed no longer relevant.
Joe Conason makes the same point:
Certainly there will be many elected officials, bureaucrats, officeholders and assorted pork-choppers who will fall into the McCain ranks without much protest, out of personal interest or partisan loyalty. If conservatives could persuade themselves to accept Romney's professions of the true faith despite his record of support for abortion rights and gay rights, then why not believe McCain when he promises supply-side tax cuts?
As Rush Limbaugh, Ann Coulter, James Dobson and their lesser imitators furiously explain, they have strong reasons to distrust "straight talker" McCain, who straddles and shifts incessantly to advance his contrarian political strategy. He has so casually disrespected them and their opinions over the years, showing up routinely on the wrong side of so many of their issues, from climate change to gun control to campaign finance reform to the marriage amendment to the Bush tax cuts to judicial nominations, that endorsing him now would look like a wholesale abandonment of principle.
Moreover, the special interests of the right-wingers' media panjandrums would be much better served by the defeat of a Republican ticket headed by McCain (especially if Huckabee becomes his running mate). In the aftermath they could argue that their party cannot win when the presidential candidate deviates from their dogma. Their profits and status would be depressed by a moderate Republican presidency, but greatly enhanced by a Clinton or an Obama in the White House.
McCain's biggest obstacle may not be Obama or Clinton but the conservatives who see a McCain defeat as a way to hang onto power within the Republican party.