Obama's speech on race prompted New Mexico Gov. Bill Richardson to endorse Obama, and other superdelegates followed.
After a stinging defeat in North Carolina and barely squeaking out a win in Indiana, Clinton vowed to stay in the race at least until the last primaries June 3, despite the fact that she trailed Obama in pledged and unpledged delegates, and her campaign was bleeding money.
The Clinton campaign announced in May that the senator had loaned herself $6.425 million -- bringing her personal loans to her campaign to $11.425 million -- making her the second biggest self-funder this election cycle, behind former Massachusetts Gov. Mitt Romney.
In a dramatic effort to woo superdelegates to his campaign, and perhaps to allay concerns that he fails to win the support of white, blue-collar workers, Obama announced he has won the coveted endorsement of his former Democratic rival, former Sen. John Edwards.
Clinton fought until the last primary contests were held in Montana and South Dakota June 3, hoping a surge of support from superdelegates -- those 797 party officials, members of Congress and state party leaders who can vote for any candidate they choose at the party's Denver convention in August -- would allow her to catch up to Obama's delegate lead.
After a bruising primary nomination contest, Obama now faces the task of uniting the Democratic Party behind him while taking on McCain and Republican opponents who have been content to watch the two Democratic candidates tear at each other during a six-month-long primary season.
A relative unknown before the primary race, Obama now faces a presidential contest against a former prisoner-of-war turned maverick GOP senator with strong defense policy credentials.
Obama goes into the general election as the new kid on the block, younger and less experienced but armed with an appealing message of hope and change against a Republican tied to the Iraq War.
The Democratic presidential candidate may also benefit from a Republican president with record-low approval ratings, and 82 percent of Americans who say the country is seriously on the wrong track.