US President Barack Obama took to the airwaves and the Internet in an 11th-hour appeal to rally support, urging young voters and minority groups to back his Democratic Party.
"Can you spend 15 minutes calling voters today to let them know how important it is that they vote?" Obama said in a message on his official account on the micro-blogging network Twitter.
Shortly afterwards, the president tweeted: "After you vote, tell your Facebook friends -- 'I voted.'"
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Democrats were nervously eyeing Tuesday's vote fearing that rival Republicans will romp home, seizing back control of the 435-seat House of Representatives and sharply narrowing the party's majority in Senate.
Millions of Americans were expected to vote Tuesday in the mid-term congressional elections, widely being seen as a referendum on Obama and his policies amid the worst economic downturn in decades.
Democrats have been working hard to get out the vote and stem the tide of Republican red expected to wash over Congress.
Obama, who visited at least five states with tight races over the weekend, also recorded a series of radio interviews aimed primarily at younger voters such as the hip-hop and rock show presented by host Ryan Seacrest.
Even though he had no official public activities, the president was heard on early morning shows in California, Florida, Illinois, Nevada, and Pennsylvania -- all states where Republicans and Democratic candidates are fighting tooth and nail.
Obama asked Hispanic voters in Nevada, where Senator Majority Leader Harry Reid is battling Tea Party and Republican candidate Sharron Angle, to swing behind the Democrats.
The "Latino vote is crucial, and obviously when you look at some of the stuff that's been going on in this election campaign, that has tried to fan anti-immigrant sentiment, I note that a lot of Latinos feel under assault," he told Nevada radio KVEG.
"My attitude is if the Latino community turns out and knows the track record of folks like Harry Reid and Dina Titus, we're going to do very well, because that's a community with a broad clout," he added.
Titus is running to be a representative in the House.
Obama also called on voters in his adopted hometown of Chicago, where the electorate is motivated by an intense battle over his former Senate seat and a contentious governor's race, to get out to the booths.
"I just repeat one more time: I need everybody to turn out to the polls today," the president told WGCI radio there.
"You can make a difference today, and how well I'm able to move my agenda forward over the next couple of years is going to depend in part on folks back home having my back."
Obama's personal appeals for support, capped an increasingly heated months-long campaign, and the get-out-the-vote efforts stepped up a notch with just hours left before the polling stations close.
The pro-Democrat Organizing for America office in Kensington, Maryland, said that volunteers on Monday had made 42,500 calls to registered Democrats, and by midday Tuesday had followed up with another 7,000.
And outside one nearby voting station in at Saint Elizabeth School, Rockville, busloads of pensioners were arriving to vote, many wielding walkers and canes.
