At first glance, the split results in Oregon and Kentucky Tuesday seemed further evidence of the primary season's chief demographic fault line. Blacks once again backed Barack Obama just as assuredly as low-income whites and older women turned out for Hillary Rodham Clinton.
Senator Clinton's support among key parts of her base – women, whites, Easterners, Hispanics, adults with no college education – dropped below 50 percent in mid-May, according to a Gallup study released this week. Senator Obama, meanwhile, has so expanded his support that he logged a record 16-point lead over Clinton in polling last weekend among Democratic and left-leaning voters, according to Gallup.
If that lead holds, it would suggest that a growing number of Clinton supporters no longer see her as a viable candidate and are coalescing around Obama as the likely Democratic nominee. The findings indicate that Democrats may have an easier time uniting behind Obama than some exit polls suggest.
"It's possible we're transitioning from the nomination phase to the general election phase," says Jeffrey Jones, managing editor of the Gallup Poll. "Instead of necessarily evaluating Obama against Clinton, he's being evaluated against McCain and therefore he may be more appealing to some Democratic groups that have been Clinton supporters."
The only key group where support for Clinton still topped 51 percent – if by a hair – were women ages 50 and older. That figure remained largely unchanged in May even while Clinton's support among men ages 18 to 49 dropped nearly 10 points.
The racial and economic rifts highlighted by the news media after a primary are heat-of-the-moment snapshots derived from exit polls. Those surveys are taken as voters leave polling places and often follow weeks of intense campaign activity, which can stir passions and deepen divisions among voters.
National polls, however, sample a broad group of voters who may have adjusted their views as passions have cooled and the race has moved on to other states.
"With exit polls, you're looking at divisions in an actual contest that just happened," says Adam Berinsky, a polling expert at the Massachusetts Institute of Technology. "The national poll is capturing the dynamics of the larger campaign."
On Tuesday, Clinton won 65 percent of the vote in Kentucky, to Obama's 30 percent, in a state whose Democrats mirrored West Virginia's: mainly white and conservative, with large numbers of lower-income, less-educated voters. Two-thirds of women voters backed Clinton, as did more than 7 in 10 whites.
In Oregon, with nearly all precincts reporting, Obama was winning 58 percent of the vote to Clinton's 42 percent. Oregonians voted by mail, but a telephone survey last week of people who said they had voted or definitely would vote found Obama drawing support from groups typically in Clinton's column.
Nearly 6 in 10 whites backed him. So did about half of women, Catholics, and voters with family incomes below $50,000. Oregon Democrats tend to be liberal, which could explain his stronger showing among those groups.
The primaries Tuesday gave Obama a national majority of pledged delegates, those awarded through the primaries and caucuses. He is now within about 60 of the 2,026 delegates needed for the nomination. At a rally in Des Moines, Iowa, Tuesday night, Obama declared himself "within reach."