John McCain may not like Barack Obama, and he definitely wants to beat Obama in this election. But McCain also thinks Obama is an admirable American. How do I know that? He has said so, repeatedly. He has promised a "respectful debate" more times that I can count. On Friday, McCain faced a supporter at a town hall who said of Obama, "He's an arab." McCain cut her off. "No, Ma'am," he said. "He's a decent family man, citizen, that I just happen to have disagreements with on fundamental issues. And that's what this campaign is all about."

The problem for McCain--and the nation--is that McCain's campaign message now systematically encourages voters to believe that Obama is secretly something awful. And on one level, that's fine. Candidates call their opponents awful all the time. That's what a competitive democracy is all about. But at the same time, McCain has a burden to be more careful than just any other candidate, given the unprecedented nature of this race. As it stands, McCain's effort to paint Obama as awful appears to be stirring up widespread racial, religious and xenophobic prejudices which are not acceptable.

In the space of one week, the McCain campaign has in one way or another, and often in misleading ways, accused Obama of a whole host of bad things that, taken alone and without context, could be seen as nothing more than hard ball politics. Obama is said to be pals with a domestic terrorist, to be trying to deny funding for American fighting troops, and to see America in a different way than most Americans. "Who is Barack Obama?" an ominous question has become the watchword of the campaign.

But taken together, and in the context of a nation still struggling to overcome a legacy of racial bigotry, the McCain message has proved problematic. Three times Friday, McCain was forced to chide his own supporters, including the woman I mentioned who called Obama an Arab and a man who said he is "scared of an Obama presidency." (TPM compiled a video montage here.) It was a bizarre situation for a major party candidate three weeks out from Election Day, and McCain should be credited for pulling back the reins.

But McCain's message strategy is unlikely to change, and he will continue to bear the burden of the uglier reactions it inspires. In the meantime, our political debate is in danger of disintegrating. On Friday, Georgia Rep. John Lewis, a civil rights icon and personal role model for McCain, posted a statement over at Politico comparing McCain to George Wallace, the segregationist governor of Alabama. "George Wallace never threw a bomb," Lewis noted. "He never fired a gun, but he created the climate and the conditions that encouraged vicious attacks against innocent Americans who were simply trying to exercise their constitutional rights. Because of this atmosphere of hate, four little girls were killed on Sunday morning when a church was bombed in Birmingham, Alabama. As public figures with the power to influence and persuade, Sen. McCain and Gov. Palin are playing with fire, and if they are not careful, that fire will consume us all."

McCain responded in a statement, saying, "I am saddened that John Lewis, a man I've always admired, would make such a brazen and baseless attack on my character and the character of the thousands of hardworking Americans who come to our events to cheer for the kind of reform that will put America on the right track. I call on Senator Obama to immediately and personally repudiate these outrageous and divisive comments that are so clearly designed to shut down debate 24 days before the election."

Hours earlier, on Saturday morning, a pastor giving the invocation for McCain at a rally in Iowa, said the following: "I also would also pray, Lord, that your reputation is involved in all that happens between now and November, because there are millions of people around this world praying to their god--whether it's Hindu, Buddha, Allah--that [McCain's] opponent wins, for a variety of reasons." This is dangerous stuff. Need anyone be reminded, Obama is a practicing Christian.

This election is going to end ugly. But let's hope it's the kind of ugly that democracies like ours are able to handle in stride, the kind where candidates and parties fight fiercely, and even unfairly, for their teams, without forgetting the basic human respect that unites us all. That ugly may be contemptible, but it does not offend our most basic ideals. The sort of ugly that McCain was forced to knock down on Friday, the sort that showed up Saturday in Iowa, that stuff is another matter altogether.