While much of the political world waits for Hillary Rodham Clinton (web|news|bio) to concede defeat, most superdelegates are done waiting. The avalanche of endorsements, expected so many times throughout the campaign, has finally materialized. Barack Obama (web|news|bio) added 51 superdelegates Tuesday, the final day of a marathon battle for the Democratic presidential nomination. He picked up 15 more Wednesday, including numerous members of Congress who said it was time to unite the party for the general election.

Clinton had a net loss of nine superdelegates over the two days.

Obama has 2,169 delegates - 51 more than needed to win the nomination at the party's national convention this summer. Clinton has 1,923.5, according to The Associated Press count.

"The most important thing our party could get out of this primary was an open and transparent process that reflected the will of the Democratic voters," Rep. Mike Doyle of Pennsylvania said in a statement. "I think the Democratic Party has accomplished this, and it's clear to me that Barack Obama has won this nomination fair and square."

Sen. Herb Kohl of Wisconsin said the party was "fortunate to have two exceptional candidates who were willing to put themselves forward and work tirelessly these many months, and for that they have our gratitude."

But, he added, "Now that Senator Obama has won the nomination, we can unite behind his historic candidacy."

Obama clinched the nomination Tuesday afternoon with endorsements from superdelegates and delegates won by former Sen. John Edwards. Edwards dropped out of the race in January and endorsed Obama in May.

Clinton won more delegates than Obama in the final two primaries, in South Dakota and Montana. She picked up a total of 16 and Obama got 15.

But the real contest was already over. Obama's campaign announced endorsements from 26.5 superdelegates as the polls closed in Montana. Many didn't want to be seen as trying to push Clinton out of the race before the final votes were cast.

There has been much focus on the superdelegates this year, ever since it became apparent that neither candidate could win the nomination without their support. They are the party and elected officials who automatically attend the convention and can vote for whomever they want, regardless of what happens in the primaries and caucuses.

A little more than 820 will attend the convention. Fewer than 140 have yet to be claimed.

Some clearly didn't relish their role.

"When voters in Oregon and around the country hear the word 'superdelegate,' people start hissing," said Sen. Ron Wyden of Oregon. "I never asked to be a superdelegate, and always thought it preposterous that my vote would be accorded greater weight than the vote of the very people who make my public service possible."

Wyden endorsed Obama on Wednesday.

Two others, from South Dakota, went the other way, giving Clinton her only two endorsements of the day.

Sen. Tim Johnson became only the second Obama superdelegate to switch to Clinton, saying he would vote for her at the convention, if she takes the fight that far, because she won South Dakota.

More than two dozen Clinton superdelegates have switched to Obama throughout the campaign, including 10 on Tuesday.