It's a generational thing. That was the theme of Barack Obama's speech last Tuesday, in which he both failed to renounce and at the same time separated himself from the man he has described as his spiritual mentor, the Rev. Jeremiah Wright.

Obama said that Wright's bellowing, "God damn America," was just a response to the evil treatment of America's blacks all those years ago by an old man (66) who does not realize, as Obama does and as the success of Obama's candidacy shows, that America is not static but has been perfecting itself.

Obama's even tone and his supple rhetoric was a soothing contrast to Wright's rants, and his calls on blacks to urge their children to read were a concession to the majority of Americans who believe that black Americans' problems are not all the fault, as Wright suggests, of vicious white people.

It was an artful performance and a politically sensitive one. For Obama's candidacy is a generational phenomenon. His greatest support comes from black voters and from voters under 30, the Millennial generation born after 1980, first named by William Strauss and Neal Howe.

The exit polls in Democratic primaries this year have shown the widest generational split that I can remember in either primaries or general elections. Upward of two-thirds of voters 65 and over have been supporting Hillary Clinton; even higher percentages of voters under 30 have been backing Obama. Evidence suggests that Obama has been attracting many new young voters -- a source of strength for his party if he is nominated -- and is even getting them to click on the campaign's emails and send in money.

The Wright sermons have probably not been a problem for Obama with black voters -- they have heard this kind of thing before. And while it may be off-putting, it will not prompt them to reconsider their votes or diminish their enthusiasm.

Millennials are another matter. In a brilliantly well-timed new book, "Millennial Makeover: MySpace, YouTube and the Future of American Politics," Democratic Party veteran Morley Winograd and media researcher Michael Hais explain how this generation, with the highest percentages of blacks, Latinos and Asians in American history, doesn't care much for racial divisions and relies for news and advice on networks of friends and peers.

A newspaper story on Obama's pastor is not going to affect their view of him -- they don't read newspapers except when a friend emails a link to a newspaper Website. A YouTube video is another thing. The Wright videos -- angry when Obama is soothing, racially divisive when Obama is inclusive, anti-American when Obama proclaims a new generation's version of patriotism -- are something else.

You can see in the national polls over the week before Obama's March 18 speech a decline in his favorable ratings, and a decline in his showing against John McCain and Hillary Clinton. The hypothesis forms that he has been losing to some extent the support and to a more important extent the enthusiasm of Millennial voters. The March 18 speech was an attempt to get that back, or at least to limit the damage.

Did it succeed? I'm not sure. Obama portrays Wright as the voice of black America for one generation, one generation that is pretty much on the way out, and himself as the voice of black Americans and of all Americans for a new generation.

But another version comes through. Readers of Obama's gracefully written autobiography, "Dreams of My Father," have been surprised to find that it is the story of a young man who wants to embrace rather than transcend his blackness. Joining Wright's church was part of that embrace.

And observers of Obama's political career will note that joining that church gave Obama political connections in the all-black South Side that he lacked as guy who arrived in Chicago from Columbia and Harvard Law, and gravitated to the mostly white university community in Hyde Park. The 76 percent black state Senate seat he won in 1996 (after getting his opponents' names removed from the ballot) included Hyde Park, but most of its voters were on the all-black South Side.

So is Obama a transcendent leader or just another politician? Millennials who have fervently believed he is the first may, after watching Wright on YouTube, wonder whether they have been wrong.

My own answer is: both. He embraced Wright for 20 years, out of something like idealism, and got something out of it. Now he is making a generational pivot away from him, with notes of idealism, and is getting something out of that, too. I'll be watching the Millennials in the next exit poll. I suspect that Democratic super-delegates will be, too.