Updated

WASHINGTON -- Desperate to curtail expected widespread losses in November congressional elections, President Obama pleaded with supporters of his 2008 campaign Monday to help elect Democrats as his aides intensified their focus on re-energizing his broad coalition of backers.

"I need your help once more," the president said in an online video sent to millions of his supporters. "If you help us make sure that first-time voters in 2008 make their voices heard again in November, then together we will deliver on the promise of change, and hope, and prosperity for generations to come."

The video announcement of what Democrats are calling "Vote 2010" is part of a multi-pronged effort by the Democratic National Committee to re-engage the legions of backers -- including first-time voters, young people, blacks, Hispanics, and independents -- who propelled Obama to victory in his groundbreaking campaign.

That won't be easy.

Democrats face a tough political environment, partly because of the economic recession and continued joblessness.

Since Obama won the White House, voters of all political stripes have soured on the president and his party; his job performance rate hovers around 50 percent and support for Democrats in Congress is even lower. The growth of government and spending increases have turned off some independent voters. Parts of the Democratic base are frustrated with the pace at which the president has made change. And some Republicans who crossed over to vote for Obama now are disillusioned.

Even some of the most senior Democratic officials don't expect that the coalition of voters who backed Obama will turn out in droves when he's not on the ballot. They didn't in three recent statewide races -- in Virginia, New Jersey and Massachusetts -- even though Obama himself made the same appeal and campaigned in those states on behalf of Democrats. Republicans won all three races.

Of particular concern for Democrats are people who were first-time voters in 2008; they're among the least likely to vote again.

Democratic National Committee Chairman Tim Kaine as well as Obama political advisers David Plouffe and Mitch Stewart were rolling out details of the 2010 campaign strategy over the next week. The party plans to spend at least $20 million -- and probably far more -- to defend its comfortable majorities in Congress.