DES MOINES, Iowa — Barack Obama declared himself "within reach" of the Democratic nomination yesterday and celebrated in the state where his win in the opening contest of the presidential primary season helped reshape the race.

Speaking to some 6,000 supporters at an outdoor rally with the Iowa Statehouse as a backdrop, the Illinois senator pointed to a campaign in which few gave him much chance of winning when he started the journey a year and a half ago. He is now the likely 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 and you have put us within reach of the Democratic nomination for president of the United States of America," he said.

Obama split a pair of primaries yesterday with Hillary Rodham Clinton. The former first lady bested him in Kentucky while he defeated her in Oregon, winning a majority of the delegates elected in all 56 primaries and caucuses combined.

Clinton took Kentucky with 65 percent of the vote to Obama's 30 percent. In Oregon, Obama was leading with 58 percent to 42 percent last night.

Obama paid tribute to Clinton in his remarks, but left little doubt that he has put the lengthy and hard-fought contest against her behind him.

"The road here has been long and that is partly because we've traveled it with one of the most formidable candidates to ever run for the office," he said, speaking of the senator from New York and congratulating her on her Kentucky win.

Obama celebrated in Iowa instead of in one of the states that held a primary yesterday as a way of "coming full circle" and launching the general election campaign in a place that is likely to be a political battleground come November.

"The same question that first led us to Iowa 15 months ago is the one that has brought us back here tonight," Obama said. "The question of whether this country, at this moment, will keep doing what we've been doing for four more years or whether we will take that different path.

"It is more of the same versus change," he said.

STARK CONTRASTS

Clinton won at least 54 delegates in the two states and Obama won at least 39, according to an analysis of election returns by The Associated Press. All 51 delegates from Kentucky were awarded but there were still 10 of 52 to be allocated in Oregon.

Obama has won 1,649.5 pledged delegates in the primaries and caucuses, surpassing the 1,627 needed to claim a majority. Three primaries remain.

Obama has an overall total of 1,956 delegates, including endorsements from party and elected officials known as superdelegates. Clinton has 1,776, including superdelegates, according the latest tally by the AP.

Obama is expected to come out of the two contests about 60 or so delegates short of the 2,026 needed to clinch the nomination. He has added nearly that many superdelegates in the past two weeks.

Obama added two superdelegates yesterday and Clinton picked up one.

White voters played a decisive role in Clinton's lopsided victory in Kentucky. Obama got the victory in more liberal Oregon, where race and the hard-edged rivalry between the two embattled candidates were muted.

Nearly nine in 10 of each state's voters were white, surveys of voters showed, but there the similarities ceased. Kentucky's less educated, poorer and more rural population fit the profile of states where Clinton has done well, while Oregon's better schooled, more affluent and urban residents more resembled those that have delivered for him all year.

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 — underscoring a challenge facing Democrats in the fall.

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 29 states where that question has been asked.

Only 29 percent of 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, 57 percent of whites backed 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 this year.

In addition, only one in 10 voters in Oregon said the race of the candidates was important, one of the lowest proportions in primary states this year.

TOUGH ROAD AHEAD

Obama warned of a tough campaign ahead against the Republicans and Arizona Sen. John McCain, their expected presidential nominee.

"They will play on our fears and our doubts and our divisions to distract us from what matters to you," Obama said. "Well, they can take the low road if they want, but it will not lead this country to a better place. And it will not work in this election. It won't work because you won't let it."

He sought unity within the Democratic Party, and with Clinton's supporters, as he looked to the fall.

"No matter how this primary ends, Senator Clinton has shattered myths and broken barriers and changed the America in which my daughters and your daughters will come of age, and for that we are grateful to her," Obama said. "Some may see the millions and millions of votes cast for each of us as evidence our parity is divided, but I see it as proof that we have never been more energized and united in our desire to take this country in a new direction."

He included a fair amount of nostalgia in his remarks, too.

"In the darkest days of the campaign, when we were dismissed by all the polls and pundits, I would come to Iowa and see that there was something happening here that the world did not yet understand," Obama said.

AP writer Alan Fram contributed to this report.