With the presidential primary season winding down, Sen. Hillary Rodham Clinton scored a sweeping victory in Kentucky yesterday even as Sen. Barack Obama, the easy victor in Oregon, reached what he called a milestone along the road to the Democratic nomination.

Speaking in Iowa, site of the stunning caucus victory that gave his candidacy liftoff 41/2 months ago, Obama hailed all that his campaign had accomplished and stopped just short of anointing himself the nominee.

"Tonight, in the fullness of spring, with the help of those who stood up from Portland to Louisville, we have returned to Iowa with a majority of delegates elected by the American people," Obama said in Des Moines, "and you have put us within reach of the Democratic nomination for president of the United States of America."

The only way he can be denied the nomination now is if the vast majority of the approximately 210 still-undeclared superdelegates turn against him. And there is no indication of that happening.

Clinton, though, continued her dominance of the Appalachian region, winning in Kentucky by nearly as big a margin as she rolled up in West Virginia a week ago. She pledged last night to keep pursuing her campaign despite the long odds that confront her.

"I'm more determined than ever to see that every vote is cast and every ballot is counted," she told cheering supporters in Louisville. ". . . That's why I'm going to keep making our case until we have a nominee, no matter who she may be."

There were 52 pledged delegates at stake in Oregon, the only state in which elections are conducted by mail, and 51 in Kentucky.

Exit polls from Kentucky showed the same kind of racial/cultural divide that has been apparent in some other states.

Overall, Clinton drew 72 percent of the white vote, Obama 88 percent of the black vote.

Clinton won 74 percent of whites without college educations, 75 percent of rural residents, and 79 percent of voters 65 years of age and up.

In Oregon, a telephone poll of voters found very different results, with Obama doing well among all but the lowest-income white voters.

As was the case in the recent primaries in West Virginia and Indiana, nearly half of Clinton's voters in Kentucky said they would not support Obama in November.

It's not clear whether those sentiments, expressed by voters in the moments after they have cast their ballots, mean very much. Nor is it clear there's a link between a candidate's performance in a primary and his or her prospects in that state in the fall.

After Obama lost the April 22 Pennsylvania primary, Clinton's strategists said that the outcome - in a state Democrats must win - should weigh heavily on the minds of undeclared superdelegates.

But a new SurveyUSA Poll for NBC10, conducted over the weekend and published yesterday, showed Obama running ahead of Republican Sen. John McCain in Pennsylvania by 8 percentage points. Two earlier surveys taken after the primary put the margin at 7 and 9 points.

Three contests remain for the Democratic candidates, with only 86 pledged delegates at stake. Puerto Rico has its primary June 1, followed by South Dakota and Montana two days later.

The biggest event left in the nominating fight is the May 31 meeting of a panel of the Democratic National Committee to consider what to do about the currently banned delegations from Michigan and Florida.

Both states staged their primaries, which Clinton won, earlier than party rules allowed. The candidates did not campaign in either state, and Obama was not on the ballot in Michigan.

Clinton is hoping the panel will seat the delegations in accordance with the outcomes of those two primaries, which would help her narrow - but not erase - Obama's lead. Even so, indications are she will get less than she wants.

Obama leads in total delegates, pledged delegates, superdelegates and states won.

The only significant measurement by which Clinton can claim a lead - and she did so last night - is the total popular vote. She leads only if the Michigan and Florida results are counted and if four caucus states, for which there's no way of knowing exactly how many people turned out, are not.

Both candidates are to be in Florida today, Obama to lay the groundwork for the fall campaign and Clinton to press her demand that the national Democratic Party recognize her victory in Florida's primary.

In keeping with a Federal Election Commission deadline, Obama yesterday reported another successful fund-raising month, bringing in $31.3 million in April to give his campaign $37.3 million cash on hand.

McCain, the presumptive Republican nominee, raised nearly $18 million last month, his best showing to date, and has almost $22 million on hand. Clinton raised $22 million, her second-best month.

In the last week, and yesterday, Obama and McCain have engaged in a general-election-style dialogue over foreign policy and other topics, leaving Clinton on the sidelines.

She has had to battle the widely shared perception that Obama is the party's likely nominee and that there's little she can do now to prevent it from happening.

In recent days, she has refrained from personal attacks on her rival, although she has criticized him for acting at times as if the nomination battle was over.

Heading into yesterday, Obama had a total of 1,917 delegates, 109 short of the 2,026 currently required to win the nomination. Clinton had 1,722.

Contact senior writer Larry Eichel at 215-854-2415 or leichel@phillynews.com.