US voters demoralised by a faltering economy look certain to hand Republicans a mid-term elections triumph on Tuesday after souring on President Barack Obama's Democrats just two years into his crusade for change.
In his hometown of Chicago on Sunday, President Obama tried to spin an optimistic picture for reporters.
"We've seen a lot of enthusiasm, but it's going to be tight. These are close races," he said. "It's true here, its true in Ohio, it's true in every state where we're competing.
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"And obviously the other side is enthusiastic. We've got to make sure our side is too," he said.
Obama's speech came a day after the much-vaunted Rally to Restore Sanity, organised by comics Jon Stewart and Stephen Colbert, staged as an antidote to the recent Tea Party-backed Rally to Restore Honor.
Reps look to gain
Polls show Republicans set to win the House of Representatives and slice into the Democratic majority in the Senate, dividing power in Washington and forging a polarised prelude to Obama's 2012 reelection bid.
Republicans, electrified by the ultra-conservative Tea Party movement, vow to reverse Obama's sweeping health reforms and promise a budget crunch and tax cuts which they claim will cut the deficit and ignite growth.
The election, for all 435 House seats and 37 in the Senate, comes as the euphoric hope Obama stirred in 2008 seems an age away and with America's trademark brash optimism drained by a narrative of national decline.
"We've tried it President Obama's way. We've tried it Washington's way. It hasn't worked. It's time to put the people back in charge," John Boehner, the likely Republican House speaker, said on Saturday.
Though Republican George W Bush was in the White House when the economy melted down in 2008, Boehner blames Obama for unemployment stubbornly pegged at 9.6 per cent due to a sluggish recovery.
But Obama reminds voters of Bush's culpability for driving the US economy into a "ditch", claims credit for staving off a second Great Depression and says his policies have put America back on the road to prosperity.
He also charges that Republicans would hand power back to predatory health insurance companies and credit card and finance barons by repealing healthcare and Wall Street reforms that add up to an already full presidential legacy.
"The other side, basically what they want to do is go back to the exact same policies that got us into this mess in the first place," Obama roared at a rally in Connecticut on Saturday.
"We have tried what they're selling right now," Obama said on a last-ditch four-state weekend tour to shore up wobbling Democrats and limit the Republican advance. "We tried it for eight years. It did not work."
Control of the House
Polls and forecasters predict that Republicans will pick up anywhere between 45 and 70 seats in the House, more than the 39 they need to gain majority, in a reverse of the huge losses they suffered in 2006 and 2008.
Control of the House would allow Republicans to thwart Obama's ambitious plans to tackle global warming and immigration reform, and to control committees which could launch damaging probes into White House conduct.
The picture in the Senate is still uncertain although Republicans look set to fall short of the 10 seats they need to take full control.
A heavy loss on Tuesday would force Obama into a period of soul searching.
He could choose to seek common ground with emboldened Republicans who have already said their top priority is to deprive him of a second term.
Alternatively, with his veto pen and the megaphone of the presidency, he could opt to stand his ground, hoping Republicans overreach.
In close Senate races, Democrats were fighting desperately against the Republican tide in California, Colorado, Pennsylvania, Wisconsin and Illinois.
The top casualty could be Democratic majority leader and Nevada Senator Harry Reid, who trails Sharron Angle, a favourite of the Tea Party movement which emerged to oppose what conservatives see as Obama's "big government" liberal agenda.
Most polls show voters favouring Republicans. A CBS/New York Times survey gave the party a 49 to 43 per cent advantage and it led Democrats 47 to 42 per cent in a recent Politico/George Washington University Battleground poll.
But voters seem to be more inclined to punish the party in power, rather than to have suddenly fallen for Republicans.
In an ABC News/Washington Post poll this month, 67 per cent of voters said they disapproved of the job Republican lawmakers were doing, compared to 61 per cent who disapproved of Democrats.
And despite a grim two years fighting economic malaise, Obama remains the most popular, active senior political leader in America, although his approval ratings in the mid-40s have declined from their stratospheric heights.
Tuesday's outcome will likely hinge on turnout, and Republicans have claimed to have the corner on enthusiasm this year.
Historically, mid-term polls are a poor indicator of a first-term president's chances for reelection.
Even before mid-term votes are cast, the 2012 race is stirring, with Republican star Sarah Palin hinting she may jump into an already crowded field.
