US presidential hopeful Barack Obama played up his foreign policy credentials while John McCain highlighted national security, as a poll on Thursday showed the Democrat hanging onto his lead in three key states.
Less than two weeks before the November 4 election, Obama made gains in Ohio while his Republican rival chipped away only slightly at the Democrat's edge in Florida and Pennsylvania, the survey by Quinnipiac University found.
As each candidate strove to highlight his opponent's weakness, the survey indicated swing state voters favor Obama on the economy by margins of eight to 19 points, and McCain on foreign policy by margins of two to six points.
Obama, flanked by top veteran military officials in Virginia on Wednesday, portrayed McCain as "out of touch and running out of time," after rejecting new Republican jibes on his plans for taxes and national security.
But McCain warned the Democratic Illinois senator not to take victory for granted, despite his mammoth financial edge and solid lead in a slew of opinion polls.
Obama is scheduled to take time out from the campaign trail Thursday in order to visit his ailing grandmother in Hawaii.
McCain also returned to his attack on recent comments by Democratic vice presidential pick Joe Biden that, just like former president John F Kennedy, Obama would be "tested" by a crisis on the international stage within six months of taking office.
The military veteran noted he had some "personal experience" with crises, citing his role in the United States' 1962 showdown with the Soviet Union over its missiles in Cuba -- known as the Cuban Missile Crisis. At that time, the Republican nominee was as a fighter pilot assigned Cuban targets.
"I know how close we came to a nuclear war and I will not be a president who needs to be tested. I have been tested," he told an enthusiastic rally on a high school football field in Green, Ohio.
McCain's running mate, Alaska Governor Sarah Palin, also took another run at Obama, ramming home the Republican claim that the Democrat would hike tax rates across the board in a "socialized" wealth sharing scheme.
"He's hiding his real agenda of redistributing your hard-earned money," she told the rally. "It doesn't sound like many of you are going to be supporting Barack the Wealth Spreader in this election."
But Obama said such attacks were distortions, and symptomatic of a McCain-Palin effort that acknowledged they were running down the clock to the election.
Obama lampooned McCain's idealized picture of "Joe the Plumber" -- an Ohio tradesman who had challenged him on his tax plans.
"John McCain likes to talk about Joe the Plumber, but he's in cahoots with Joe the CEO," Obama said in Richmond, the first of two stops in the southern state of Virginia, which normally votes Republican but where he is leading in the polls.
The new clashes over tax came on another sickening day for the US economy, with stocks diving on grim company data, sparking fears of a global recession as the broad-market Standard & Poor's 500 index hit a five-year low.
McCain sought to portray Obama as taking the electorate for granted, given a clutch of favorable polls and the massive 150-million-dollar warchest he amassed in September.
"My opponent's looking pretty confident these days," McCain said in New Hampshire, a state which revived his moribund presidential campaign earlier this year.
"He'll be addressing the nation soon. He's got another one of those big-stadium spectacles in the works, acting like the election is over."
But in a chilly evening rally before an estimated crowd of 35,000 in Virginia, Obama rebuked supporters for falling prey to the triumphal mood.
"I am superstitious, I don't like counting those chickens before they hatch."
The Quinnipiac poll showed Obama ahead of McCain in Florida by 49 to 44 per cent, compared to a 51-43 per cent lead in the last survey October 1, and in Pennsylvania Obama leading 53-40 per cent, compared to 54-39 per cent last time.
McCain lost ground in Ohio, where Obama leads 52-38 per cent, expanding his lead of 50-42 per cent at the beginning of this month.
"If these numbers hold up, he could win the biggest Democratic landslide since Lyndon Johnson in 1964," said Peter Brown, assistant director of the Quinnipiac University Polling Institute.