Next week's battle for control of the US Congress could turn on people like Karen Roper, who are working to get Americans off their sofas and out to the polls.

Roper and an army of other ordinary citizens are on the front lines of a final, frenetic push by both Republicans and Democrats to encourage their supporters to vote - an effort that could mean the difference between victory and defeat in dozens of close races.

Republicans say they will need a strong turnout among conservatives to hold on to Congress in the face of widespread dissatisfaction with President George W. Bush and the war in Iraq. It's a tall order, analysts and even some organisers said, despite the Republican Party's traditional advantage in fund-raising and getting out the vote.

Cincinnati physical therapist Linda Kopko, a registered Republican, said corruption scandals have also discouraged many party loyalists. "That's why the Republican turnout is going to be very low. I think they're very discouraged with what's going on," she said. In Silver Spring, Maryland, Roper said she encountered a lot of enthusiasm at Democratic households she visited at the end of October. "They were angry at the Republicans, let's put it that way. If anything they were very psyched to vote Republicans out," the business consultant said.

With control of Congress at stake, both parties are spending millions of dollars on the efforts, which can increase a candidate's share of votes by as much as nine per cent. Democrats have traditionally relied on labour unions and other independent advocacy groups to handle voter mobilisation. But after stinging losses in 2002 and 2004, the Democratic National Committee created its own voter database and set up staff positions in all 50 states.

Polls show Democrats stand a good chance of picking up the 15 seats needed to win control of the House of Representatives, and could win the six seats necessary to control the Senate as well. A Wall Street Journal/NBC News poll this week found 47 per cent of registered voters had been contacted by political parties or candidates; one in five had heard from both sides. Get-out-the-vote efforts can play a disproportionate role in midterm races, which typically see lower voter participation than elections in which the presidency is at stake.

While 61 per cent of eligible voters participated in the 2004 presidential election, only 40 per cent voted in 2002, according to American University's Center for the Study of the American Electorate.

In Montana, Republicans hope to boost turnout by around 10 per cent to help Sen. Conrad Burns retain his Senate seat, and Republicans in Michigan plan to campaign door-to-door in heavily Democratic Detroit for the first time since 1962.

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