It's in the nature of campaigns to careen from the totally unexpected to the utterly unthinkable, but recent events in the presidential contest probably ought to be filed under the heading: "With friends like these."

By Friday, all three candidates had been forced to apologize for the offensive views of a prominent supporter. John McCain was first, when one of the evangelical ministers whose approval he has so assiduously courted turns out to have some inconvenient views. John Hagee, a prominent Texas televangelist, also happens to teach that the Catholic Church is "the whore of Babylon" and a "cult."

McCain, who appeared with Hagee on television to accept his endorsement, tried to brush off the matter. Better judgment — and, perhaps, consideration of the Catholic vote's importance — prevailed, and the senator told The Associated Press: "I repudiate any comments that are made, including Pastor Hagee's, if they are anti-Catholic or offensive to Catholics."

Hillary Rodham Clinton was next up, when former congresswoman and vice presidential candidate Geraldine Ferraro told an interviewer: "If Obama was a white man, he would not be in this position." Clinton tried several apologies and, Wednesday — after Ferraro had resigned from the campaign's finance committee — finally got it right: "I certainly do repudiate it."

It was Obama's turn Thursday, when, after a network television report, video clips began circulating of sermons by the Rev. Jeremiah A. Wright Jr., the recently retired pastor of the senator's Chicago church, Trinity United Church of Christ. In one, Wright raves: " 'God bless America.' No, no, no, God damn America. . . ." In another, he fumes that the 9/11 attacks were a consequence of using atomic weapons against Japan and for U.S. support of "state terrorism against the Palestinians and black South Africans."

Obama, who in other contexts has tried to compare Wright to a loutishly eccentric old uncle, told an interviewer that the quotes were the result of "cherry picking" the pastor's many sermons. By Friday, though, the senator and his campaign had begun to understand that his association with Wright is problematic in ways neither Hagee nor Ferraro were for McCain and Clinton. For one thing, the video clips of Wright's inflammatory homilies are caught up in the new media loop. They're all over the Internet, the cable news shows and right-wing talk radio. They have "gone viral."

Moreover, because America is never more segregated than it is on Sundays, Wright's ranting is going to hit white Americans with particular force. Every big city has one or more black pastors like Wright who mix left-wing conspiracy theories, phony Afro-centricism, remnant black power rhetoric and a rag bag of vulgar Third World sympathies in an angry, frequently race-baiting social gospel. Preached in a style that leaves little room for understatement, it's alarming stuff when you hear it for the first time. And because the U.S. news media don't take anybody's religion very seriously or report on it in much depth, this will be many white Americans' first exposure to this inflammatory — albeit tiny — tendency within black churches.

Then there's the fact that, while Hagee and Ferraro were bit players in their campaigns, Wright hasn't been a tangential figure in Obama's life. The senator sought the church out and made a personal profession of faith in response to Wright's preaching. Obama has said he consults Wright before making important political decisions.

The Illinois senator is nothing if not an adroit campaigner, and he clearly understood that an Internet firestorm required an Internet backfire. So late Friday he published a blog on the Huffingtonpost that called Wright's remarks "inflammatory" and "appalling." He went on to write: "I vehemently disagree and strongly condemn the statements that have been the subject of this controversy. I categorically denounce any statement that disparages our great country or serves to divide us from our allies. I also believe that words that degrade individuals have no place in our public dialogue, whether it's on the campaign stump or in the pulpit." Obama also said he had decided to remain a member of Trinity because Wright has retired.

Once again, Obama has demonstrated how well he understands that much of his campaign's appeal is built on an ability to speak about race and social solidarity in a new way, to make change and hope again coincidental in the American political psyche. He knows that nobody will follow you into a new era if they suspect you're carrying the reeking baggage of the old.

Tim Rutten is a Los Angeles Times columnist. Reach him at timothy.rutten@latimes.com.