This story was written by CBSNews.com political reporter Brian Montopoli.
According to American Conservative Union chairman David Keene, is not what you'd call a conservative's conservative.
"There's this personal animosity he has towards people over issues," said Keene, who has endorsed. "Most conservatives see that he would like to remake the party without them."
Despite a voting record that suggests he should be in conservatives' good graces - he has an 82.3 percent lifetime rating from Keene's ACU - McCain has strident critics within the conservative establishment. Among them are Former House Majority Leader Tom DeLay, Former Sen. Rick Santorum (who has vowed to support any Republican but McCain), and a host of conservative talk radio hosts led by Rush Limbaugh, who has suggested a McCain nomination would "destroy the Republican Party."
Much of their disenchantment is tied to the positions McCain has staked out on hot-button issues. McCain's relative moderation on immigration led his onetime rival in the GOP race, Tom Tancredo, to suggest that McCain "is one of the most dangerous threats we have." His sponsorship of campaign finance reform legislation has prompted outrage from conservative advocacy groups who see it as a limit on free speech. And his longtime opposition to the Bush tax cuts, characterization of conservative religious leaders as "agents of intolerance," decision to partner with Joe Lieberman on global warming legislation, and bipartisan Senate compromise on judicial nominees have all generated anger from the right.
But the animosity towards McCain stems from something deeper than just his positions. The Arizona senator's ACU rating is only six percentage points behind Santorum's, and his voting record is conservative enough that he's been able to line up support from well-respected conservative Republicans like Tom Coburn, Phil Gramm and Sam Brownback.
For many, McCain's style is the problem: He not only breaks with conservative orthodoxy on issues that many conservatives consider basic tenets of the movement, but he does it with a "finger in your eye" style that alienates them even further.
"He's tough to deal with, there's no doubt about it," said Randy Pullen, chairman of the Arizona Republican party, citing McCain's general unwillingness to compromise. "He believes what he believes in, and he wants other people to support him in those beliefs."
"Some of his battles are so intense and loud that it sort of increases the animosity," said GOP strategist Greg Mueller. "You've got these intense issues where a lot of rhetoric gets tossed around and it breeds resentment."
Keene said "those who've worked with [McCain] get the sense that he doesn't like conservatives."
"In his world, it's very difficult to have a simply policy disagreement," Keene said. "Everything becomes personal. His position is right, and everyone else's is basically evil."
McCain's defenders say that the conservative establishment's skepticism towards McCain grows out of his unwillingness to defer to them.
"McCain has never kowtowed to them or anybody else," said McCain strategist Charlie Black.
"I think with Rush Limbaugh and some of them, they're always looking for a perfect conservative," added Black. "They see that as their job. And nobody's perfect."
Some of the anger towards McCain could be personal. McCain launched the Jack Abramoff investigation that sank DeLay, and his focus on eliminating pork barrel spending may have alienated some of his Senate colleagues.
"John McCain couldn't win a popularity contest in the Senate if he tried," Senator John Warner, a McCain supporter, said on Tuesday. "Why? Because he cuts too much government spending."
According to McCain press secretary B.J. Boling, any disenchantment with McCain among the conservative establishment has not been reflected among the rank-and-file.
"Just take Greenville County [South Carolina] for example," said Boling. "Bob Jones University, North Greenville University, and a few theological seminaries are located in Greenville - it's practically the buckle of the Bible Belt. It's home to some of the largest evangelical congregations in the state, and John McCain came within three points of defeating a former Southern Baptist minister [in] there."
But McCain, who courted South Carolina's conservative establishment, has largely been dependent upon moderate and independent voters in the early contests. Mueller argues that his campaign needs to do more to consolidate support among the conservative base.
"Just because they found one county in South Carolina where the vote was closer to them, I hope they're not taking that to the bank," Mueller said. "They're going to need to do a lot more than that with conservatives. You want the base energized, want them mobilized. You're going to need every vote."
McCain and his surrogates have made some overtures to skeptical conservatives by stressing that McCain will pick strict constructionist judges as president.
"It's a huge issue for Republicans, a party crossing issue," said Mueller. "The next president could appoint two, three, even four Supreme Court judges. If McCain goes out and talks about that, it's going to be a reminder to the conservative base of the party - 'who do you want picking your judges?'"
Conservative Republican media strategist Craig Shirley, who is supporting McCain, says the opposition will dissipate if McCain wins the Republican nomination.
"Winning is a great antidote to bruised feelings and strained relations," said Shirley. "What he's got to do is keep articulating his conservative positions. And keep the lines of communication open with everybody. And everybody in the end is hopefully going to play nice."
Black puts it more bluntly.
"All these conservative leaders will be for him in two weeks when we lock up the nomination," he said.
By Brian Montopoli