"All my life I have wanted to vote for a woman for president," Clinton told 800 parishioners at the Temple of Praise congregation in Washington. "All my life I have wanted to vote for an African-American for president. ... I wonder why God gave us this dilemma."
Mr. Clinton cited his wife's experience and policy initiatives in housing, education, heath care and voting rights for the District of Columbia and called Hillary Clinton "the best qualified person to be president I've had an opportunity to vote for."
At a service at Greater Mt. Nebo AME Church in Bowie, Mr. Clinton asked several hundred parishioners to think and pray about their choice.
Mr. Clinton's wife, Sen., D-N.Y., is facing off against Sen. , D-Ill., in primaries Tuesday in Maryland, Virginia and the District of Columbia.
Asked outside the church what he thought of Saturday's results, in which Obama swept victories in Louisiana, Nebraska and Washington state, Mr. Clinton seemed unfazed.
"I lost Washington state in 1992 also," Mr. Clinton said.
At the Bowie church, parishioner Michael Gaddy said Mr. Clinton made a good speech, but nevertheless he is going to support Obama.
"It's not a dilemma for me," Gaddy said. "I think Obama's the better man for the job. If for some reason he doesn't get the nomination, I think we'd all be behind Hillary."
Mr. Clinton joined Maryland Gov. Martin O'Malley at the crowded Battle Grove Democratic Club in Dundalk, a Baltimore suburb, Sunday afternoon where the former president fought through a power failure that briefly cut out the lights and microphone.
Mr. Clinton said his wife would repair the nation's image abroad by embracing diplomacy instead of military force.
"From now on, we're going to have diplomacy with friend and foe alike whenever we can, and military force will be used only as an absolute last resort, not the other way around," he said.