President Barack Obama slammed "cocky" Republicans as he launched a last-ditch weekend campaign to stave off a humiliating defeat for his Democrats in mid-term elections.

Obama, who spent the day Friday dealing with a cargo plane terror scare, headlined an earsplitting evening rally in Virginia, on the eve of a four-state tour to shore up Democrats wobbling ahead of Tuesday's congressional polls.

Republicans are tipped to seize the House of Representatives and pare back the Democratic majority in the Senate in the election, which could road block Obama's presidency two years after voters gave him a mandate for change.

But Obama beseeched Americans to confound the polls and accused his political foes of plotting to revive the policies that got America into its worst economic "mess" since the 1930s Great Depression.

"They are feeling kind of cocky right now ... the Republican leader in the House said this is not a time to compromise," Obama said, opening fresh hostilities with John Boehner, who is likely to be Speaker if Republicans win.

Obama also seized on a comment by Senate Republican leader Mitch McConnell that his party's top priority in the new Congress would be to help the eventual Republican party presidential candidate in 2012.

"The Republican leader of the Senate said that his main goal for the next two years, his top priority, is to beat me in the election," Obama said.

"He didn't say 'my top priority is to create jobs' ... he is already thinking about the next election and this one is not over yet."

"That's what's wrong with Washington ... that's the kind of cynicism that we are fighting against."

Obama's event amounted to a last-ditch rescue mission for Virginia congressman Tom Perriello who may lose his job on Tuesday after backing some of the president's sweeping reforms on which the public has soured.

"You can defy the conventional wisdom," Obama roared to supporters, painting Perriello as a rare man of courage in Washington's cynical political jungle.

Republicans are widely expected to net more than the 39 seats they need to take over the House of Representatives in Tuesday's election but fall short of the 10 seats they need to recapture the Senate.

Obama planned to launch a final weekend campaign blitz on Saturday, campaigning inConnecticut, Illinois and Pennsylvania, and in Ohio on Sunday, in a bid to drive up Democratic turnout and save some seats.

Earlier, new data showing only modest US GDP growth offered scant consolation for Obama and his Democrats, as they look set to pay a heavy price at the polls for high unemployment and the sluggish economic rebound.

Commerce Department figures showed that real GDP grew at 2.0 percent in the third quarter, a slight rise on the second quarter but still far from the roaring growth Democrats had banked on presenting to voters.

Speaking in Maryland, Obama said the figures showed the economy was on the mend, but more needed to be done to address unemployment, currently at 9.6 percent.

"As we continue to dig out from the worst recession in 80 years, our mission is to accelerate that recovery and encourage more rapid growth... and we can get the millions of Americans who are still looking for jobs back to work," Obama added.

A survey by The New York Times and CBS television on Thursday found that, by a broad 61-34 margin, respondents believed America was on the "wrong track" as it struggled to emerge from the economic downturn.

The poll found nearly two in three respondents willing to back political newcomers on November 2, and 28 percent more ready this year to back someone with views that "seem extreme."

This video is from the White House, published Oct. 30, 2010.