Barack Obama passed a major milestone to move within reach of the U.S. Democratic presidential nomination on Tuesday, but rival Hillary Clinton refused to surrender.
A split of two nominating contests -- Obama handily won Oregon and Clinton crushed the front-runner in Kentucky -- gave Obama a majority of pledged delegates won during their lengthy state-by-state nominating fight.
Obama hoped the milestone marked the beginning of the end of the grueling battle, and he turned his attention to a general election matchup with Republican John McCain in November.
"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," Obama told a rally in Iowa, site of his breakthrough victory in the first Democratic contest on Jan. 3.
The Illinois senator, 46, returned to the theme of change that propelled him to the front of the Democratic race during the early contests. He described the battle with McCain, 71, as "more of the same versus change. It is the past versus the future."
But Clinton gave no sign she was ready to quit.
"I'm going to keep making our case until we have a nominee -- whoever she may be," Clinton said, promising supporters in Kentucky that she would keep fighting until the Democratic voting ends on June 3.
"We have to select a nominee who is best positioned to win in November and someone who is best prepared to address the enormous challenges in these difficult times," the New York senator and former first lady told supporters in Louisville.
Even after Tuesday's votes are counted, Obama will still be about 70 delegates short of the 2,026 needed to win the nomination at the Democratic convention in August.
But he hopes the pledged-delegate milestone will push more undecided superdelegates -- party officials who can back any candidate -- his way. Obama contends those superdelegates, who have been breaking his way heavily in recent weeks, should support him because he won the most delegates in state voting.
Clinton says they should reconsider because she would be a stronger opponent against McCain, an Arizona senator. Her victories in big states like Pennsylvania and Ohio gave her a broader base of support than Obama, she said.
"Neither Senator Obama or I will have reached that magic number when the voting ends June 3," Clinton said of the number of delegates needed to win the nomination. "So our party will have a tough choice to make."
Obama aides said he could reach the magic number with a wave of superdelegate endorsements in the next two weeks. Three more contests remain -- Puerto Rico on June 1 and Montana and South Dakota on June 3 -- with a combined 86 delegates at stake.
Both candidates head on Wednesday to Florida, a major battleground in November. Clinton is still fighting for the seating of delegates from Michigan and Florida, where she won contests that were not recognized by the national party. Their seating would narrow Obama's lead in the race.
"I'm going on now to campaign in Montana, South Dakota, and Puerto Rico, and I'm going to keep standing up for the voters of Florida and Michigan," she said.
Clinton also hopes her continued drubbings of Obama in states like Kentucky, where she won by 35 points, will give superdelegates pause.
Exit polls showed Obama, who would be the first black U.S. president, had difficulty with white working-class voters in Kentucky as he has in some other states. Clinton won more than 70 percent of white voters, and three-quarters of those who did not finish college.
About 20 percent said race played a factor in their vote -- similar to the percentage last week in West Virginia, where Clinton trounced Obama.
A delegate count by MSNBC gives Obama 1,941 delegates to Clinton's 1,772. He had 1,636 pledged delegates, with 1,627 representing a majority.
Obama's success has been fueled by record fundraising. He reported raising $31.3 million in April, down from the $42.8 million he raised in March, and had $37.3 million in the bank to fund his campaign, his campaign said.
Tuesday was the deadline for filing monthly financial reports with the Federal Election Commission. The Clinton campaign said it raised $22 million in April, up slightly from $20.9 million in March.
The campaign has admitted to being more than $20 million in debt and did not say how much cash it had or still owed.