The junior U.S. Senator from Illinois is "a real agent of change, he's a bridge to the future and he can lead our nation in a new and positive direction," Lee, D-Oakland, told reporters on a conference call.
She said she holds all the Democratic contenders in high esteem, but in the end "it really was a matter of conscience."
In a written statement, Lee said she's confident Obama "would find a prompt and effective way to end the occupation of Iraq and that he would strengthen US diplomacy and international development as an instrument of national policy to prevent crises that lead to war and conflagration.
"I know that a President Obama would place education, health care, economic security, criminal justice reform, climate change and all of the important domestic issues at the top of his agenda," she said. "And, I know that a president Obama would make eradication of HIV/AIDS at home and abroad a top priority."
Obama has refused to vow to have all U.S. troops out of Iraq by the end of his first term in the White House, but Lee said on Monday's conference call that "Senator Obama was against this occupation and this war early on."
"I, for one, believe we need to bring our young men and women home now, we do not need to provide one more dime of funding for this occupation," she said, adding that she doesn't agree 100 percent with any of the Democratic candidates' platforms but believes Obama's most closely matches her views.
"I intend to work very hard to make sure that he wins," she said.
Lee spoke at Obama's big St. Patrick's Day rally in Oakland's Frank Ogawa Plaza, but also appeared at U.S. Sen. Hillary Clinton's big downtown Oakland rally Sept. 30. Clinton on Oct. 1 collected the endorsement of Lee's political mentor, Oakland Mayor Ron Dellums; Clinton also has the endorsement of another Dellums protege and her own former chief of staff, Assemblyman Sandre Swanson, D-Oakland.
"Mayor Dellums, Assemblyman Swanson, myself, (Alameda County) Supervisor (Keith) Carson -- we're very close... and of like mind in terms of politics and our vision and our commitment to the future," Lee acknowledged Monday.
But they're individuals and need not be in lockstep on endorsements, she said. "I respect the mayor's and Assemblyman Swanson's decisions. ... We will continue to be friends, we will continue to work together on the issues we care so much about."
Mitchell Schwartz, Obama's California campaign director, noted Monday that Lee "represents more registered Democrats than any other Congressional district in the state: more than 200,000 in her district."
Lee's staunch antiwar stance -- including her lone vote against authorizing military force days after the Sept. 11, 2001 terrorist attacks -- has proved popular in her district and other Democratic strongholds, but has proved controversial in some other places.
Yet Lee said she and fellow congresswomen and antiwar leaders Maxine Waters and Lynn Woolsey have been warmly received in Iowa, a crucial early-caucus state where Obama is in a dead heat with Clinton. And she said her work to combat poverty -- she chairs the Out of Poverty Caucus -- and increase access to quality education and health care "reflects where the American people are" and should resonate with early-primary voters nationwide.
Obama is scheduled to be at Universal CityWalk in Los Angeles tonight for a "Generation Obama" concert/fundraiser wherein thousands will pay $25 or $50 to see the likes of the Goo Goo Dolls, Ne-Yo and other notable entertainers. Clinton has a fundraiser today in Los Angeles as well, and will be in San Francisco Tuesday for a big-ticket luncheon fundraiser hosted by billionaire investor Warren Buffett.
A nationwide Associated Press-Ipsos poll conducted Dec. 3-5 found Clinton backed by 45 percent of Democrats, followed by Obama at 23 percent, John Edwards at 12 percent and Bill Richardson at 4 percent, with a 4.5-percentage point margin of error. In California, a SurveyUSA poll conducted Nov. 30-Dec. 2 found Clinton at 50 percent, Obama at 24 percent and Edwards at 16 percent, with a 3.6-percentage point margin of error.
--Contact Josh Richman at email@example.com or 510-208-6428. Read the Political Blotter at www.ibabuzz.com/politics