Carol Ann Campbell, a former Philadelphia city councilwoman, said she made up her mind Saturday after receiving a telephone call from the Illinois senator's wife, Michelle.
The women talked for nearly 90 minutes about the problems of the handicapped, children being raised by their grandparents and the importance of religion in their lives. Campbell said she decided on the spot to support Obama over New York Sen. Hillary Rodham Clinton "because of the level of comfort" she felt.
"She never once said, `Will you support him?"' said Campbell, who uses a wheelchair. "She left it open to me to talk to her about what I considered important."
In superdelegate canvassing by The Associated Press, Campbell previously had said she was undecided.
With Campbell's endorsement, Obama is backed by three of the 26 superdelegates selected so far. Clinton has been endorsed by 13 and the rest are neutral.
Campbell said she admires former President Bill Clinton and his wife, but that Sen. Clinton's campaign was not as aggressive in soliciting her support or learning about her concerns.
Campbell, who heads Philadelphia's black ward leaders, said she is particularly concerned about international hostility toward the United States and suggested that electing the nation's first black president might ease that.
Nationally, there are about 800 superdelegates - elected officials and party leaders chosen outside the primaries and caucuses who are not bound to support a particular candidate at the party's presidential nominating convention in August. Because of the very close contest between Obama and Clinton, their votes could wind up deciding which candidate becomes the nominee.
State party Chairman T.J. Rooney, who is backing Clinton, suggested that superdelegates may turn out not to be as influential as some are predicting.
"I think everybody ought to just take a deep breath, sit back, take a pill if they need to, and understand that it's over two months to the Pennsylvania primary" on April 22, he said.
Pennsylvania is sending 187 delegates to the Democratic convention. The vast majority - 158 - will be elected by party members in the primary or selected in June by the Democratic State Committee in proportion to the statewide presidential preference.
The state committee will also pick the state's last three superdelegates in June.
