The one week countdown to the most hardfought presidential election in history gets underway Tuesday with Barack Obama and John McCain vowing to fight to the finish for every last vote.
The White House rivals were to hold competing rallies Tuesday in the rust-belt state of Pennsylvania before splitting, with Republican McCain fighting a rearguard action in North Carolina and Obama heading to Virginia.
Despite holding a robust poll lead nationally and in battleground states, Democratic nominee Obama, 47, warned against complacency as he prepared to air a costly 30-minute "infomercial" on major US networks Wednesday evening.
"Don’t believe for a second this election is over," the Illinois senator bidding to be America’s first black president said Monday in Pittsburgh, whose withered steelworks are symptomatic of Pennsylvania’s industrial blight.
"We can’t let up. Not now. Not when so much is at stake," he added in what aides called his "closing argument" to voters.
Obama’s caution appeared to be justified by a new poll Tuesday which suggested the race was tightening.
The Zogby poll of 1,202 likely voters had Obama’s lead shrink nearly a point to 49 percent, while McCain fell 0.4 points 44.7 percent. The number of undecided voters had risen to 6.3 percent, up 4.9 percent from 24 hours earlier.
For McCain, Pennsylvania and its swollen ranks of disaffected, white, working-class voters is must-win territory on November 4, along with historically Republican bastions such as North Carolina and Virginia.
The Arizona senator, 72, vied to reignite fears of "socialism" by citing a 2001 radio interview given by Obama where he appeared to lament the failure of the 1960s civil rights movement to bring about greater financial equality.
"That is what change means for Barack the Redistributor: It means taking your money and giving it to someone else," he told a rally in Dayton, Ohio.
The challenge facing McCain was underlined by his choice this late in the game to head to North Carolina, which has not voted for a Democratic White House hopeful since 1976 but is now a raging battleground.
Virginia is an even deeper shade of Republican "red," having last backed a Democrat for the presidency way back in 1964. But Obama has a double-digit poll lead there, and is hoping the forecasts could portend a landslide in his favor.
The Republican was to address a rally in Fayetteville, North Carolina, home of the vast Fort Bragg army base, as the former Vietnam prisoner of war hammers Obama as unfit to serve as commander-in-chief.
"I have fought for you most of my life, and in places where defeat meant more than returning to the Senate," McCain said in Dayton.
"There are other ways to love this country, but I’ve never been the kind to back down when the stakes are high."
Obama, vowing to pull US forces out of Iraq and expand the Afghan theater, has been going toe to toe on national security with McCain — but is driving the economy as the defining issue of this historic election.
Against the backdrop of an increasingly ugly election campaign, US justice authorities said Tuesday that two white supremacists had been arrested for threatening to assassinate the Democrat during a "killing spree" of more than 100 African-Americans.
Daniel Cowart, 20, and Paul Schlesselman, 18, were arrested last week in Tennessee for possession of firearms, threats against a presidential candidate and conspiring to rob a gun store, federal officials said Monday.
Meanwhile there was uproar in the Los Angeles gay enclave of West Hollywood after a Halloween display showed a figure resembling Republican vice-presidential pick Sarah Palin hanging by a noose.