By Mark Willen, Senior Political Editor April 15, 2008 Despite the furor over Barack Obama's "bitter" comments, he's picked up another superdelegate -- Nancy Larson, a Democratic National Committee member from Minnesota. --That cuts --As Clinton shows she can be tougher than Obama as a campaigner, her support within her core group -- white women -- is slipping, with many in Pennsylvania saying they are unhappy with her negative approach. She's lost six percentage points with that group in a week, according to a Quinnipiac University poll taken April 3-6 in Pennsylvania.. --While much of the attention in Pennsylvania is on blue collar voters in the rural middle of the state, the real battle is in the Philadelphia suburbs. More than 60% of Democrats live in the Philly metro area. About 40% are African Americans, and there are big concentrations of highly educated upscale liberals and students -- all strong Obama supporters. And the Economist notes there is also a concentration of high-tech companies with younger employees drawn to Obama. He needs to rack up a huge lead in the Philly area to overcome Clinton's edge elsewhere. But it can be done. In fact, that's exactly what John Kerry did in 2004 to take Pennsylvania away from Bush, who won all of the rural and blue collar counties.