But the original sin of racial discrimination never stays out of our national conversation for long, and last week even Obama couldn't duck the subject. By an accident of scheduling, he spoke Thursday to the National Urban League, one of the nation's oldest civil rights organizations. It was only a week after the embarrassing episode of Shirley Sherrod, in which Obama's administration forced a black official to resign over a bogus charge of reverse racism.

Here's what Obama said: "We've made progress. And yet, for all our progress … we were reminded this past week that we've still got work to do.

"We should all make more of an effort to discuss with one another, in a truthful and mature and responsible way, the divides that still exist, the discrimination that's still out there, the prejudices that still hold us back."

And where should that discussion happen? "Not on cable TV, not just through a bunch of academic symposia or fancy commissions or panels, not through political posturing, but around kitchen tables and water coolers," the president said.

But not, you may notice, in the White House, and not with Barack Obama at the table.

This president is an activist. He hasn't hesitated to use his power — and his bully pulpit — to reshape the nation's financial system, its healthcare system and (if he gets his way) its energy sector. He seized control of GM and Chrysler. He even offered advice to the NCAA on a college football playoff.

But talking about race relations? Not his job.

His press secretary, Robert Gibbs, has spent two weeks deflecting questions with a nonexplanation: "I don't think the president has to be the teacher at every teachable moment."

Obama's allergy to talking about race relations is understandable.

He won the presidency, in part, by not talking about race. Most of the time, he didn't have to. Part of his appeal was his gift of being not only African American but biracial and even post-racial. He embodied the promise of racial healing. Vote for Obama, the not very subliminal message went, and we will be a better country by the close of election day. His biography and his appearance made the point better than words.

Only when events demanded did Obama tackle race head on during the campaign — in Atlanta in January 2008, when he spoke at the Rev. Martin Luther King Jr.'s Ebenezer Baptist Church to establish his African American bona fides, and in Philadelphia in March, to quell the furor over the intemperate sermons of his pastor, the Rev. Jeremiah A. Wright Jr. Even then, Obama didn't really try to launch a national conversation about race; he delivered eloquent monologues, and moved on to other issues.

Since his inauguration, the president and his White House have treated the hot-button issue of race mostly as a dangerous distraction from the business they wanted to focus on. When Atty. Gen. Eric H. Holder Jr. made headlines excoriating Americans as "cowards" about confronting race, the White House wasn't pleased. When Obama accused a police officer of behaving "stupidly" by arresting Harvard professor Henry Louis Gates Jr., the gaffe required a beer summit. Last month, when Agriculture Secretary Tom Vilsack asked Sherrod to resign, it was a hasty attempt to head off another racial controversy at a time when the White House wanted the national conversation to be about financial regulation.

If any further proof was needed, Obama and his aides need only look to their most bitter opponents. Some of the president's right-wing critics appear desperate to change the subject to race. Their argument, in the words of Fox News Channel's Glenn Beck, is that Obama "has a deep-seated hatred for white people or the white culture.... This guy is, I believe, a racist." Don't look for evidence to back up that poisonous charge; there isn't any. But Beck and others seem to think that by repeating it, they can not only erode Obama's legitimacy as a racial healer but convince white voters that he's anti-them. And anti-majority politicians don't win many elections.

Obama has every reason to keep himself offstage when the issue is race. Being a "normal" president — by focusing on policy and legislation rather than race relations — has been one of his signal achievements. To most of white America, he's just the president, not the black president. In most of the country, the conversation isn't about whether Obama is favoring blacks or whites or anyone else; it's about whether his stimulus plan can work and whether he's running too big a deficit.

But that doesn't mean we don't also need to talk about racial equality and ethnic diversity. Who could lead such a dialogue in a civilized, useful way? Bill Clinton, who launched a similar conversation in 1997, could help. Gates, the Harvard professor, knows a thing or two. Or Jim Webb, the Democratic senator from Virginia who's criticized diversity programs for favoring high-income minority candidates over low-income whites. Or Rep. John Lewis (D-Ga.), one of the surviving heroes of the civil rights movement that made Obama's presidency possible.

The president doesn't need to teach on every issue. But on this one, he might consider asking someone else to.