Mr Edwards said Mr Obama had done well enough without his endorsement
Former Democratic US presidential hopeful John Edwards has said that Senator Barack Obama is now his party's "likely presidential nominee".
But he has stopped short of endorsing Mr Obama, saying that the value of endorsements is "greatly inflated".
After Mr Obama's victory in this week's North Carolina primary and narrow loss in Indiana, observers say he is poised to win the nomination.
But his rival Hillary Clinton has vowed to go on "until a nominee is chosen".
Mr Edwards refused to reveal which candidate he voted for in Tuesday's Democratic Party selection contest in North Carolina, his home state.
But, speaking on US television, he said Mr Obama has "the capacity... to unite the Democratic Party [and] to bring in new voters, to bring in people who haven't been involved in the process over a long time and to get people excited about this change".
And although he did not formally endorse the Illinois senator, he joked that Mr Obama "has done pretty well without any endorsement from John Edwards".
Mr Obama is leading the race for the delegates - who will choose the presidential nominee at the party's nominating convention in August - by 1,854 to 1,697, according to the AP news agency.
Since Tuesday's primaries, Mr Obama has picked up the support of a number of the senior party officials and lawmakers - often referred to as "superdelegates" - who get an automatic vote at the convention by virtue of their position.
One of his new endorsements came from New Jersey congressman Donald Payne, who had previously backed Mrs Clinton.
"I have reached the conclusion that Barack Obama can best bring about the change that our country so desperately wants and needs," said Mr Payne.
Mr Obama now trails Mrs Clinton among superdelegates by only a narrow margin, according to AP.
As of 1800 BST he had received the backing of 267 superdelegates to Mrs Clinton's 271.5, it said.
Mrs Clinton on Wednesday pledge to remain in the race "until the nominee is chosen" did not reveal whether this meant she would stay in until the party's nominating convention in August.
But as details emerged of a $6.4m (£3.2m) loan that Mrs Clinton had given to her campaign last month, commentators suggested that the New York senator faced a funding crisis.
Contributors will not throw money at what they see as a lost cause, says the BBC's Justin Webb, and without daily infusions of cash, presidential campaigns cannot survive.
Mrs Clinton also faced criticism for comments she made in an interview with the USA Today newspaper about Mr Obama's electoral prospects among white voters.
"Senator Obama's support among working, hardworking Americans, white Americans, is weakening again," she told the newspaper.
Her remarks were described by Obama campaign spokesman Bill Burton as "frankly disappointing".
The two candidates are locked in a drawn-out battle to stand for the Democratic Party against Republican John McCain in November's presidential election.
Neither candidate is likely to win enough pledged delegates - who are bound by party rules to vote for the candidate that the majority of the voters in their state supported - to clinch the nomination.
The outcome therefore hangs on the decision of the nearly 800 superdelegates, who are free to choose for themselves which candidate to back.
The Clinton campaign is hoping that it can still persuade a majority of the remaining undecided superdelegates to back the New York senator.
Her team are also still arguing that the delegates from Michigan and Florida - barred by party chiefs from attending the convention after the states broke party rules by holding their contests early - should be allowed to take their seats at the convention after all.
Mrs Clinton did well in the disputed contests, and would benefit if the party opted to overturn its earlier ruling.
There are just six primary contests left: West Virginia, Oregon, Kentucky, Puerto Rico, Montana and South Dakota.