Sen. Barack Obama (D-Ill.) got glowing reviews when he addressed the issue of race last month in Philadelphia.

But there are aspects of the race issue in this campaign that still make people nervous.

Recently I called a number of political strategists of both parties, as well as unaffiliated experts, to ask whether Democrats have been voting along racial lines in this year's primary season.

After all, 92 percent of black Democrats in Mississippi voted for Obama, while 91 percent of black Democrats in Wisconsin did the same. And 70 percent of white Democrats in Mississippi voted for Sen. Hillary Rodham Clinton (D-N.Y.), as did 64 percent of white Democrats in Ohio.

That seemed kind of, well, racial. But when I asked the question, people tended to demur.

"It's more class versus race," a Democratic strategist told me.

"No, it's not racial," a Republican consultant told me. "Most people are still looking for someone who they can identify with, someone who shows an understanding of their lives. I think calling it racial would be a gross oversimplification."

"I think it's some broader sort of cultural sense," another expert told me.

It's fair to say that is the conventional wisdom on the subject.

But the issue of voting along racial lines is perhaps the issue in the Democratic presidential primary contest.

And the question of the moment is: Will white Democrats in Pennsylvania vote along racial lines?

If they do, Hillary Clinton will stay alive to fight in North Carolina, where the question will be: Will white Democrats vote along racial lines?

If North Carolina's substantial black Democratic electorate votes as black Democrats have done in other states — around 90 percent for Obama — the only way Clinton can win is if white voters go substantially in her favor. That is, if they vote along racial lines.

As the quotes above suggest, it's something that makes many of us uncomfortable. We don't want to think that voters are making their decisions on the basis of race.

And there are certainly questions of class and culture involved. But race is undoubtedly a factor.

And if Obama is the nominee, it will become a huge issue for Republicans, because Obama will likely inspire a historic number of black Americans to vote.

Black voters were about 10 percent of the 105 million people who voted in the 2000 presidential election.
Al Gore got 90 percent of that black vote.

Black voters were about 11 percent of the 121 million people who voted in the 2004 presidential election.
John Kerry got 88 percent of that.

What about next time, if Obama is on the ticket?

"I think it would be up pretty substantially," David Bositis, a senior political analyst at the Joint Center for Political and Economic Studies, told me.

And of that higher black turnout, Obama could win even more than the already sky-high percentages that Gore and Kerry received.

"I could see him getting 94 percent," Bositis added. "The high was 94, which is what Lyndon Johnson got in 1964, although it was a much smaller black vote then."

That kind of turnout could make a difference in key states like Ohio and Missouri.

And then the question will be: What will white voters do? Will they vote like white Democrats in Mississippi and Ohio? Or like white Democrats in Wisconsin, who voted 54 percent for Obama?

It's something political analysts will be talking about a lot, whether it makes them uncomfortable or not.