Obama's advantage over McCain in a prospective general election contest stems from his strong support among voters under age 65, among women and independents. Among African Americans, Obama leads McCain 80% to 3% with 18% undecided or favoring someone else, but McCain leads among white voters by a 47% to 41% margin, with 12% undecided or favoring someone else.
Hillary Clinton, however, does not fare so well...
In a prospective McCain/Clinton match-up, McCain wins easily, 50% to 38%. His lead is based upon a 59% to 32% advantage among men, compared to Clinton's narrow 44% to 41% edge among women. While McCain trails Obama among every age group under 65, he leads Clinton in all age groups - his biggest advantage coming among those ages 30-49, where he enjoys a 53% to 35% edge.