Racial and social tensions exposed by the Democratic White House duel are splitting the party at its core, despite attempts by Barack Obama and Hillary Clinton to turn the bile on Republicans.
Both Democratic champions went out of their way to pledge a united struggle to defeat Republican presumptive nominee John McCain in November, even as their showdown raced to an acrimonious end with two endgame primaries Tuesday.
But exit polls in Kentucky, where Clinton won big, and Oregon, which was Obama country, laid bare chasms in the party, near the end of a race which has seen the two party heavyweights split its constituencies right down the middle.
In Kentucky, which is less educated and poorer than Oregon, racial tensions are still close to the surface. It also fits the profile of largely white blue-collar states where Clinton does well, hence her 35-point win.
Oregon, on the west coast, is more liberal, more affluent and educated -- factors making it an ideal demographic for Obama.
As in her other big wins, in states like Ohio and West Virginia, Clinton's populist persona as tireless fighter for the working class paid off.
Obama meanwhile looked to have serious work to do to connect with this important constituency, which plays a big role in general election swing states.
Exit polls for US television stations in Kentucky found that only a third of Clinton supporters in Kentucky would vote for Obama over Republican presumptive nominee John McCain in November.
Even more worrying for the Illinois senator, who is vying to become America's first black president, a racial component was evident in the state -- as it had been in earlier battlegrounds like West Virginia.
Only three in 10 white voters in Kentucky who cited race was a factor in their decision said they would back Obama in a matchup with McCain in November's general election.
In Oregon, though, Obama won every category of voters, exit polls showed, apart from Clinton's narrow win among one of her most faithful groups -- white voters 60 years and older.
Obama, with his once unlikely quest for the nomination nearing fruition, tried to paper over the rancor between Clinton's supporters and him.
"We have had our disagreements during this campaign, but we all admire her courage, her commitment, and her perseverance," he said in his victory rally in Des Moines, Iowa, a key midwestern swing state.
"Senator Clinton has shattered myths and broken barriers and changed the America in which my daughters and yours will come of age."
The choice of Iowa, where Obama won the leadoff nominating contests to catapult him into the political stratosphere, was symbolic.
The midwestern state is one of the whitest in America, and is also a swing state in the general election -- and far more likely to swing Democrat than Kentucky, or West Virginia in November.
Clinton, who for months implied that Obama might be a soaring speechmaker but had a threadbare record of results, has now toned down her attacks, as her hopes fade, and also sought a measure of reconciliation.
"I commend Senator Obama and his supporters, and while we continue to go toe-to-toe for this nomination, we do see eye-to-eye when it comes to uniting our party to elect a Democratic president in the fall," she said in her victory rally in Louisville, Kentucky.