Even as Obama edges toward his party's nomination, Kentucky underscored his ongoing struggle to chip away at Clinton's dominance among whites -- including the better educated ones who have been a tossup group between the two rivals.
Sixty-three percent of white college graduates backed Clinton in Kentucky, according to exit polls of voters. Only in Arkansas have more favored Clinton among the 33 states that have held Democratic primaries in which both candidates competed.
Three quarters of whites who have not completed college -- a bulwark of Clinton support this year -- also backed the New York senator. She has seldom done better this year with those blue-collar white voters.
Just 45 percent of whites in Kentucky said they would vote for Obama in a matchup with John McCain in the general election.
Racial attitudes were also striking. About one in five whites in Kentucky said race played a role in choosing their candidate -- on par with results in other Southern states. Nearly nine in 10 of that group backed Clinton -- the highest proportion yet among the 28 states where that question has been asked.
Only three in 10 whites in the state who said race was a factor said they would vote for Obama should he oppose McCain in November.
All that contrasted with Oregon, where a majority of voters called themselves liberal.
According to telephone interviews with the state's voters, who cast all their ballots by mail, nearly six in 10 whites were backing Obama. The Illinois senator and Clinton were evenly dividing working-class whites -- those who have not finished college -- a group that has decisively stuck with Clinton in most states this year.
In addition, only about one in 10 white voters in Oregon said the race of the candidates was important, one of the lowest proportions in primary states this year. They were evenly divided between the two Democrats, but heavily backed Obama when he was pitted against McCain.
As the battle for the Democratic nomination finishes its fifth month, there were signs some voters are looking beyond the contest's end.
Just over half in Kentucky said they expect Obama to win the party's nomination -- including one in three Clinton backers. In Oregon, three quarters predicted Obama would be nominated, including just over half of those backing Clinton.
Like most states, Kentucky displayed the distaste each candidate's supporters had for the rival contender, underscoring a challenge the party will face in uniting its voters for the fall election.
Only a third of Clinton backers there said they would vote for Obama against McCain. Obama voters seemed more forgiving -- seven in 10 said they would vote for Clinton.
Heads seemed cooler in Oregon. There, seven in 10 Clinton backers said Obama would get their vote against the Arizona Republican, while eight in 10 Obama backers said they would support Clinton against McCain.
In Kentucky, just four in 10 Clinton supporters favored picking Obama as running mate should she win the nomination. The same number of Obama backers want Clinton to run as his vice president. The question wasn't asked in Oregon.
Further illustrating the two states' differing perceptions, Clinton was seen by most as more honest than Obama and as the candidate who most shares voters' values in Kentucky. The reverse was true in Oregon.
In Kentucky, Clinton dominated Obama across virtually all categories of voters, winning strongly among men, women and whites, as well as people of virtually all ages, income and education levels. Obama took nine in 10 blacks.
In Oregon, the only groups Clinton controlled were people over age 65 and those earning less than $30,000 a year -- voters who have been loyal to her almost all year.
Kentucky voters saying John Edwards' endorsement last week of Obama was important were split evenly between the two contenders, while those saying it was insignificant backed Clinton heavily. The question wasn't asked in Oregon.
The Kentucky data came from an exit poll by Edison Media Research and Mitofsky International for The Associated Press and television networks conducted in 30 precincts in the state. The data was based on 1,407 people voting in Kentucky's Democratic contest, with a margin of sampling error of plus or minus 4 percentage points.
The Oregon figures came from telephone interviews the companies conducted of 1,201 people voting in that state's contest, with a margin of sampling error of plus or minus 4 points. The interviews were conducted from May 12-18.