"We're going to be having a conversation in coming weeks, and I'm very confident how unified the Democratic Party's going to be to win in November," he told reporters after a vote in the Senate where he received congratulations from all sides.

Meanwhile, the dam holding back endorsements broke from coast to coast on the day after the primary elections concluded.

Seven senators who had stayed out of the matter said they were giving Obama their commitment and would work toward uniting Democrats for the election, now exactly five months away.

In Nashville, Tennessee Gov. Phil Bredesen was joined by two other superdelegates to say they hoped to bring the party behind Obama even though Clinton won their state. Former Vice President Walter Mondale, who had been a Clinton supporter, announced he was backing Obama.

In this February 26, 2008, file photo, Barack Obama, right, and Hillary Rodham Clinton, enter the stage during their debate in Cleveland. After Obama secured the nomination Tuesday, June 3, 2008, he called Clinton in the evening and left a message. [Agencies]

It hardly mattered in terms of delegate math – after months of struggle, Obama had more than enough to prevail at the party convention in Denver in August. But Obama's new backers were also sending a message to Clinton that her race was over.

Bob Johnson, the founder of Black Entertainment Television, was lobbying members of the Congressional Black Caucus to urge Obama to place Clinton on the ticket. He said he was doing so with her blessing.