"Barack has the skills and experience that's necessary to really challenge the status quo in Washington, D.C.," Miller said before a press conference Wednesday in San Francisco. "I'm very encouraged by the energy of the people responding to him and his vision of how people can come together to solve the problems that confront us."

Miller cited Obama's extensive grassroots fund-raising campaign, first-place win the Iowa caucus and strong showing in the New Hampshire primary, leadership style and opposition to the Iraq War.

In other East Bay congressional districts, Rep. Barbara Lee, D-Oakland, has come out in support of Obama, while Rep. Ellen Tauscher, D-Alamo, is supporting Clinton. Reps. Jerry McNerney, D-Pleasanton, and Pete Stark, D-Fremont, have not endorsed anyone.

Contra Costa County Supervisor Susan Bonilla also announced her endorsement of Obama during Wednesday's event.

Miller's decision to back Obama comes as no philosophical surprise, although the congressman had indicated several months ago that he might not endorse in the Democratic primary.

Both men have been opposed to the Iraq War since its inception, one of the hallmark issues in Miller's progressive Bay Area district.

But Miller is also a renowned champion of women in politics -- he is a top advisor to House Speaker Nancy Pelosi, D-San Francisco -- and it would not have appeared too odd if he had thrown his name behind the first woman to seek the presidency, New York Sen. Hillary Clinton.

"Why not help elect the first woman president?" Miller said. "That can be argued. But why not elect the first African-American?"

As for the experience factor that has been the bedrock of Clinton's campaign, Miller, who has served in the House of Representative for more than 30 years, says that longevity in Washington does not always translate into leadership.

"Obama's experience in looking at the evidence led him to conclude that the Iraq War was not a war we should engage in, while Clinton looked at the same evidence and concluded that we should engage in it," Miller said.

"The number of years in (office) is neither here nor there. What matters is the leadership to reach the scores of independent voters and across the political lines to make change.

"I've watched both campaign and I know both candidates and I believe Obama offers us an opportunity to truly change the way we do business in Washington."

Miller also looked at the candidacy of former North Carolina Senator John Edwards but says he did not "see the people responding (to Edwards) in a way that will make his campaign viable in the general election. This is about putting together a campaign in the primary that can win in the general election."