As vultures circle the McCain campaign, the conventional wisdom about his demise is that Iraq brought him down. As Arianna Huffington wrote,

John McCain's cratering campaign is an object lesson in how to kill a candidacy in three simple steps: 1) locate the biggest foreign policy disaster in U.S. history 2) embrace it 3) implode. (Bonus step: spend money like you are Paul Bremmer).

But Glenn Greenwald doesn't buy that analysis because the GOP base still supports the war:

The war in Iraq remains popular with the GOP base. They want to stay and keep waging war. They would immediately turn against anyone who advocated withdrawal or even questioned the wisdom of staying. The Republican Party continues to be the Party of the Iraq War, and -- directly contrary to the conventional wisdom that is arising -- loyal support for the Iraq War is an absolute pre-requisite for winning the nomination.

Chris Bowers weighs both arguments and triangulates by looking at independent voters who support McCain:

Compared to other Republicans, McCain has always enjoyed disproportionate support from Republican-leaning independents, "true" independents, and even Democratic-leaning independents. His primary base of support, both in terms of polls and fundraising, has a far more independent, purple hue to it than that of any other Republican. Thus, given the sharp independent turn against the Iraq war over the last two years, not to mention the Indycrat phenomenon of the same time period (a trend that was first identified by Jerome Armstrong), his hawkish positions made him far more out of step with his base of support than other top-tier Republicans. His base of support made him more immediately vulnerable to a hawkish position on Iraq, and that is why his campaign imploded first.

Of the three positions, Greenwald is right because Greenwald alone looks at the voters who matter to Republican candidates who are seeking the Republican nomination: Republican voters. And here is how Republican voters have leaned since the 2004 election:

As the graph makes clear, McCain was never the frontrunner - Giuliani has led the race from the start. Why? Because the #1 issue for Republican voters is fear of terrorism, and Giuliani's entire campaign is based on that fear, starting with his keynote address to the Republican Convention in 2004. 

Fear of terrorism powered Bush's 2004 campaign, which drew overwhelming GOP support despite Bush's failure to find WMD's in Iraq and the growing insurgency that was killing U.S. soldiers every day. And of course that fear was constantly stoked by Tom Ridge's color-coded terror alerts, as Ridge later admitted.

Nevertheless, McCain was running a remarkably steady second place until January, when his support began to drop. And what caused the drop? As the blue line demonstrates, it was Fred Thompson's entrance onto the Presidential stage.

I'm going to speculate here because I don't have enough data to work with. Here's what I know from today's AP-Ipsos poll:

None of the top candidates has a clear lead among Christian evangelicals, a critical part of the GOP base that has had considerable sway in past Republican primaries. Giuliani, a thrice-married backer of abortion rights and gay rights, had 20 percent support — roughly even with Thompson and McCain who have one divorce each in their pasts. Romney, a Mormon who has been married for three decades, was in the single digits.

It looks me like White Protestant Republicans (especially evangelicals) never loved McCain, but they stuck with him until they had a better White Protestant Republican - namely Thompson. 

Why wouldn't WPR's support Giuliani? Because he's Catholic - and pro-choice, pro-gay, and pro-divorce to boot. Why not Romney? Because he's Mormon, even if he defies Mormon faith by accepting Jesus as his savior.

A more interesting question is why WPR voters ignored the other WPR candidates - Mike Huckabee, Sam Brownback, Tommy Thompson, and the now-departed Jim Gilmore. All of them are reliable Christian Conservatives, all smart, attractive, and articulate, yet none have risen above background noise in the polls.

Perhaps, as Greenwald points out, Brownback hurt himself with the pro-war GOP base by questioning the war. Huckabee's fatal flaw was raising taxes in Arkansas, thereby violating another sacred principle of the GOP. Perhaps there were just too many of them dividing the hard-core evangelical vote.

But here's an even more abstract theory: perhaps none of them could appeal to the media and financial elites in Washington DC and New York City, so they never got the "buzz" they needed to emerge from the pack.

Fred Thompson was able to appeal to the media elites simply because of his acting career, and so he got the buzz.

And when you analyze evangelicals, you discover the Hollywood aura is more important than ideology and "values." After all, it was Ronald Reagan who brought evangelicals into Republican politics in the late 70's and 80's, even though he was the first major Presidential candidate who was ever divorced.

The strength of Thompson's Hollywood aura will be put to the test when he ends his campaign striptease and formally declares his campaign. Thompson isn't entering the race as a conservative virgin - he's already been tagged as lazy, with a morally suspect "trophy wife," and a tawdry career as a lobbyist for "abortionists" and Haiti's "demon" president Aristide.

It's no surprise that evangelical voters are mostly watching and waiting. Looking at the GOP candidates, they have no one to love, but also no one to hate. It's entirely possible the next Republican candidate will not be "annointed" by evangelical voters, which could allow a Christian Democrat like Clinton or Obama to get enough evangelical votes to win.

Update 1: Greenwald makes a deeper point that I'm struggling with: that the Iraq War is a religious war, both in Bush's mind and in the minds of his evangelical followers.

Everything we do in the Middle East has religious and theological overtones. Whatever else is true, we are sending a largely Christian army into Muslim land to wage war against devotees of Islam. Many of the President's evangelical supporters are explicitly supportive of this militarism because of a generalized belief in the need to wage religious war (the Gen. Boykin view) or the specific doctrinal belief in the need to re-make the Middle East in preparation for apocalyptic events. That applies not only to Iraq, but to Iran and the broader Middle East.

While Greenwald cites examples of Bush claiming divine guidance, I don't think Bush perceives the Iraq War as a crusade of Christians against Muslims or as preparation for the Apocalypse, and he certainly never says such things. What he did say is "I do believe there is an Almighty, and I believe a gift of that Almighty to all is freedom." He also uses his press conferences to attack the view that the passion for freedom is limited to Christendom and is missing from the Muslim world.

So if the Iraq War isn't a "crusade" in Bush's mind, I don't hink it's a "crusade" in the mind of the GOP base either. So why are evangelicals the only ones who still support it?

I'd pinpoint the motivation as fear of terrorism, rather than religious zeal. Since 9/11, there has been a profound and palpable fear of Muslim terrorists in America's heartland. Those of us who live in the cities most likely to be targeted (like New York) think this fear of attack in the heartland is exaggerated and irrational. But simpler minds are less able to calculate the actual odds of being hit by a terrorist, so the incessant fearmongering on TV goes a very long way towards keeping heartland Christians in a permanent state of fear.