WASHINGTON -- The movement of Democratic superdelegates to presidential hopeful Barack Obama gained steam Friday with endorsements from a union president and two congressmen, including one who switched his backing from rival Hillary Rodham Clinton.

Obama has now climbed within a handful of superdelegates of catching Clinton in endorsements from the party and elected officials who will ultimately decide the nomination. With the three new superdelegate endorsements, the superdelegate count is Clinton, 271.5 and Obama, 266.

Obama also picked up the endorsement of the influential American Federation of Government Employees union on Friday.

"Our people, I think, recognize the enthusiasm and vitality behind Senator Obama's campaign," AFGE President John Gage said.

Gage, a previously uncommitted superdelegate to the Democratic National Convention, said he is also personally endorsing Obama.

In New Jersey, Donald Payne -- a black congressman who had been backing Clinton for the nomination -- is switching his support to Obama, Dan Pfeiffer, a spokesman for the Obama campaign, confirmed.

Rep. Peter DeFazio of Oregon also plans to formally endorse Obama and campaign with him at events Friday in Eugene and Albany, Ore.

"Senator Obama has proven he is able to energize young Americans, independents, and even moderate Republicans to support his candidacy," DeFazio said in a statement released by his office. "I believe he represents our best hope of winning in November, and puts the needs and priorities of hard working Americans ahead of the powerful special interests that have been extraordinarily favored by the Bush-Cheney administration."

Oregon counts its mail-in primary ballots on May 20. While polling in the state has been sparse, Obama is believed to hold a significant advantage over Clinton. With DeFazio, he will have the endorsement of three of the state's four Democratic House members. Reps. Earl Blumenauer and David Wu earlier endorsed Obama, while Gov. Ted Kulongoski and Rep. Darlene Hooley have endorsed Clinton.

Clinton won the New Jersey primary on Feb. 5 and has strong backing from the state's congressional delegation.

"After careful consideration, I have reached the conclusion that Barack Obama can best bring about the change that our country so desperately wants and needs," Payne told The Star-Ledger in Newark, N.J. It was "one of the most difficult decisions I have made," Payne said. "I've really been mulling it over for quite a while."

Obama's endorsements from superdelegates has picked up sharply since Tuesday, when he soundly defeated Clinton in North Carolina's primary and held her to a narrow victory in Indiana.

Clinton continues to pickup superdelegate endorsements, including one from a Pennsylvania congressman on Friday.

Rep. Chris Carney noted that Democrats in his northeastern Pennsylvania district supported Clinton by a more than 2-1 margin in the state's April 22 primary.

"I will respect their decision," said Carney, who represents a historically Republican district and is viewed by the GOP as vulnerable to a fall challenge.