Barack Obama is poised to reach a major milestone in the Kentucky and Oregon primaries today — a majority of the elected delegates offered in the Democratic presidential contest.
But Hillary Clinton soldiered on despite her dwindling hopes.
Mrs Clinton was vowing to continue the fight through the last primaries in early June, cheered on by a group of supporters from the WomenCount political action committee who took out a full-page ad in
The New York Timesurging her not to give up.
But, Senator Tom Daschle, a key Obama adviser, argued that the party should be coming together in support of Obama in order to beat certain Republican nominee John McCain in the November general election.
Democrats have worried that the prolonged, and frequently combative, primary campaign has given McCain a free ride to focus on November.
Clinton is favoured to win by a large margin in Kentucky as voters cast their ballots there, while Obama was expected to take Oregon. Regardless, Obama was assured that he would be able to claim the largest share of elected delegates who could be won in the long slog of votes since January.
The Illinois senator's campaign is touting the milestone as a big step toward ending the epic nomination battle with Clinton.
Having a majority of delegates elected in state primaries and caucuses could help Obama's case with undecided superdelegates — the party insiders who are not tied to primary or caucus results — to pick up the pace of their endorsements.
Superdelegate support is crucial because neither candidate will have enough delegates from the remaining primaries to clinch the nomination without them.
Obama added another superdelegate to his column earlier today, Guam congressional delegate Madeleine Bordallo.
Including superdelegates, Obama had 1,917 delegates to Clinton's 1,721 goes into today's primaries in which 103 delegates are at stake in the two states. By tomorrow morning, Obama could be just 50 to 75 delegates short of the total 2,026 needed to nominate a candidate at the party's national convention in Denver in late August.
Mr McCain has already been targeting Obama in his campaign speeches as his likely opponent in the November election.
Yesterday the Arizona senator accused Obama of inexperience and reckless judgment for saying Iran does not pose the same serious threat to the United States as the Soviet Union did in its day.
Obama has been increasingly presenting himself as the nominee as he looks ahead to the battleground swing states in the general election.
Tonight, he is holding a rally in Iowa, where he won the leadoff caucuses in early January.
Since Iowa, Obama has won 1,610.5 elected delegates — leaving him just 17 short of a majority of the 3,253 pledged delegates up for grabs. He is sure to cover the gap in today's primaries because the delegates are allocated proportionately.
Of the nearly 800 superdelegates, about a quarter of them have not declared support for either candidate.
Clinton has mounting campaign debts, but she vowed there was "no way that this is going to end anytime soon" as she campaigned yesterday in Kentucky.
The New York senator soldiered on through event after event, ending her night in Louisville before a crowd of several hundred, her voice raspy.
"There are a lot of people who wanted to end this election before you had a chance to vote," she said, husband and former President Bill Clinton at her side. "I'm ready to go to bat for you if you'll come out and vote for me."
Obama, seeking to become the first black US president, has also won the endorsement of Sen Robert Byrd of West Virginia, the longest-serving senator in history and a former member of the white supremacist Ku Klux Klan and one-time opponent of civil rights legislation.
Nationally, Obama holds his largest lead yet over Clinton in the Gallup Poll, 55 per cent to her 39 per cent. In mid-January, Clinton held a 20 per cent lead in the Gallup Poll.
After today, only three primaries remain on the Democratic calendar. Puerto Rico, with 55 delegates, holds its primary on June 1st; Montana, with 16 delegates, and South Dakota, with 15, vote two days later.