Gallup has this poll out today with some interesting news on both race and gender in the presidential contest. Not surprisingly, Gallup’s most recent poll shows Obama’s continued weakness among white voters, not only overall, but within certain key subgroups.

For example, the survey shows McCain leading among whites overall by 15 points against Obama, but only holding a 9-point edge over Clinton if she were the Democratic nominee.

Both Obama and Clinton’s deficits balloon among white males in a match-up against McCain. Gallup reports both Democrats trail the Arizona Senator within this group by a whopping 21 points (57%-36%).

But it’s among white women where the Obama and Clinton supporters diverge in a head-to-head contest with McCain. The Arizona Senator leads among white women by 16 points (51%-35%) against Obama. Yet against Senator Clinton, McCain merely ties at 46%-46%.

It’s ironic that a candidate such as Obama -- whose rhetoric and strategy relies so much on building unity -- generates such stark racial cleavages among Americans.