By Mark Willen, Senior Political Editor April 29, 2008 It may be impossible for a white person to understand what is motivating the Rev. Jeremiah Wright as he goes about ruining Barack Obama's chances for winning the presidency. And make no mistake, that is exactly what he is doing. From the start, Obama cast himself as a politician who wanted to transcend both partisan and racial politics and bring Americans together to work on common problems. The question has always been whether he -- or anyone -- could actually do that. When he succeeded in inspiring a whole new generation of voters, many Democrats and more than a few independents and Republicans thought it was worth a giving him a chance. It was always a long shot because the country is so divided on demographic, as well as ideological grounds, as David Brooks points out in the New York Times today. But Obama at least had a chance. Success, though, meant that Obama couldn't run as a traditional black candidate in the sense that that he couldn't focus on the anger of the past and make claims for apologies and retribution, justified or not. He had to look to the future and focus on how to bridge differences and start fresh, to the extent that was possible. That is what he was saying in his speech in Philadelphia last month. Some whites never wanted to let him get away with that, however, and now they've been joined by Rev. Wright, whose comments focus entirely on the past and include many allegations that very few Americans can live with, including the notion that we brought 9/11 on ourselves and that the U.S. govenment has intentionally spread AIDS. In repeating these claims, Wright has given Obama's opponents enough ammunition to overwhelm any candidate, and it is hard to see how Obama can survive. He may hold on to win the Democratic nomination, but the fall campaign will feature Wright's comments played over and over again. Even a complete denunciation of Wright by Obama won't mean much at this point, given their long history. He can argue as much as he wants that he's not responsible for what Wright says, but he'll have a hard time getting a lot of people to accept that. That leaves me wondering just what Wright was thinking. I can understand his wanting to defend himself, but that seems pretty selfish if it means destroying the chances of the first African-American to have a chance of winning the presidency and getting into a position to make real change, however hard that will be. Wright has forced the debate back to the angry 1960s and 1970s, which can't lead to any kind of progress. In fact, it's likely to lead to a lot of regression and bitterness and polarization. That seems awfully selfish, and terribly disappointing, no matter how you feel about Obama and the Democrats. The bottom line is that Rev. Wright can't do anything at this point to help his flock. And thanks to him, the chances that Obama can are diminishing rapidly.