WASHINGTON — Senator Obama, undeterred by a lopsided Kentucky defeat at the hands of Senator Clinton, is claiming a near-victory in the Democratic primary fight, declaring last night that the party’s presidential nomination is “within reach.”

As Mrs. Clinton beat Mr. Obama by 35 points in the Kentucky primary, the Illinois senator stood in Iowa — the site of his first victory in January — to celebrate the milestone marked by his clinching the majority of pledged delegates at stake in the Democratic nomination.

“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,” Mr. Obama said in prepared remarks, in words meant to signal that the primary was all but over.

Mr. Obama made little mention of the results in Kentucky, where he had campaigned only sparingly in a population heavy with the white, working-class Democrats who have yet to embrace his candidacy. With 97% of the precincts reporting, Mrs. Clinton was leading, 65% to 30%. The primary represented her second blowout victory in as many weeks; she carried West Virginia, a state with similar demographics, by 41 points on May 13.

Mr. Obama was favored to win the day’s other contest in Oregon, where the results were not known at press time because the election was conducted entirely by mail.

Speaking to supporters in Louisville, Mrs. Clinton once again stated her intention to battle for the nomination through the final primaries in Montana and South Dakota on June 3. Without criticizing Mr. Obama, she urged party leaders to choose her as the most electable Democrat. “After all this country has been through the last seven years, we have to get this right,” she said, adding that she “passionately” believed a Democrat had to capture the White House this fall.

“I am going to continue making my case until we have a nominee, whoever she may be,” Mrs. Clinton said, putting extra emphasis on the feminine pronoun as her supporters roared.

Both candidates opened their remarks with salutations for Senator Kennedy, hours after news spread that the Massachusetts lawmaker and party elder was diagnosed with a malignant brain tumor.

Mr. Obama has campaigned with party unity in mind in recent weeks, and last night he made his most pointed effort to pay tribute to Mrs. Clinton and her historic candidacy. “We have had our disagreements during this campaign, but we all admire her courage, her commitment and her perseverance,” he said. “No matter how this primary ends, Senator Clinton has shattered myths and broken barriers and changed the America in which my daughters and yours will come of age.”

With 103 delegates at stake in Oregon and Kentucky, Mr. Obama was expected to finish the contests needing well under 100 total delegates to reach the magic number of 2,026 to secure the nomination. With Mr. Obama clinching a majority of pledged delegates, Mrs. Clinton will need an overwhelming percentage of the remaining undecided superdelegates to give her any chance at the nomination.

She is also pushing for the seating of the Florida and Michigan delegations, which the Democratic National Committee stripped after the states held early primaries in violation of party rules. Mrs. Clinton won the elections, but both were uncontested and Mr. Obama was not on the ballot in Michigan. Her campaign is hoping a party committee convening on May 31 will overturn the initial sanctions and seat the delegations according to their primary results.

Despite calls by some party leaders in recent weeks for Mrs. Clinton to drop out, it now appears certain she will stay in the race until the final contests in two weeks.

“She firmly believes she has a path to victory here,” a national finance chairman of her campaign, Hassan Nemazee, said in an interview yesterday.

Mrs. Clinton’s top fund-raisers voiced “uniform” support for her remaining in the race when they met in Washington last week, even as they acknowledged the odds were stacked against her, Mr. Nemazee said. “We are not delusional. We know what the reality is. She is also not delusional.”