Barack Obama warned supporters against "giddy" complacency on Thursday, before plunging into the 19-day home stretch of the White House race with snap polls awarding him yet another debate victory.

Following late Wednesday's third and final debate before the 4 November election, the Democrat said that Republican John McCain was obsessed with maligning his character instead of thrashing out "the issues that matter."

"Last night, Senator McCain said that (President) George Bush won't be on the ballot this November," Obama told a rain-soaked outdoors rally.

"But let's be clear: his policies will," the Illinois senator said.

"Because in three debates and over 20 months, John McCain hasn't explained a single thing that he would do differently from George Bush when it comes to the most important economic issues we face today. Not one."

Barrage of attacks

The front-running Democrat largely dodged a fierce barrage of attacks from a feisty McCain in their last debate clash before the foes began blitzing battleground states ahead of the election in just under three weeks.

The pair were set to meet again late on Thursday at a dinner in New York to raise funds for underprivileged children. Each was to deliver remarks at the white-tie event, but partisan sniping was not expected to be on the menu.

Earlier, Obama invoked the trauma of his primary defeat in New Hampshire to Hillary Clinton in January, which came as euphoria and expectations exploded around his campaign after a stunning lead-off victory in the Iowa caucuses.

"For those of you who are feeling giddy or cocky or think this is all set, I just have two words for you: New Hampshire," said Obama, who is in a dominant position in national and local polls, at a breakfast fundraiser in New York.

"I've been in these positions before when we were favored and the press starts getting carried away and we end up getting spanked.

"That's another good lesson that Hillary Clinton taught me, so we want to make sure that we are closing strong, running through the tape."

Probably not coincidentally, Obama headed directly after the breakfast to New Hampshire, where Clinton's victory locked the nominating race into a grim six-month struggle, and which is now a general election toss-up state.

McCain in Pennsylvania

McCain meanwhile landed in Pennsylvania and was later heading to nearby New Jersey, two states which the Arizona senator had been hoping to peel out of the Democratic column but which look more and more solid for Obama.

Most snap polls after the debate gave Obama a clear victory, as he stayed cool under a broadside of McCain attacks on his character and policies, designed to rescue the Republican's flagging campaign.

In CNN's poll, 58 percent of respondents said Obama won the debate compared to 31 for McCain, with 70 percent saying Obama was more likeable. A CBS poll scored the debate 53-22 percent for the Democrat.

McCain used the debate to make his most effective attempt yet to frustrate Obama's efforts to link the Arizona senator with the unpopular legacy of his fellow Republican, Bush.

"Senator Obama, I am not President Bush. If you wanted to run against President Bush, you should have run four years ago," McCain said, proclaiming his record of bucking the Republican line in contrast to Obama's inexperience.

'100 percent negative' tone

McCain, down by double digits in most polls as the United States weathers its worst financial crisis in decades, savaged Obama's ties to 1960s radical William Ayers and said his tax plans were nothing more than "class warfare."

McCain (72) also assailed the liberal group Acorn, whose canvassers are accused in several states of adding fraudulent names to voter registration lists.

Obama (47) accused McCain of trying to distract voters on a day that New York's Dow Jones share index posted its second-biggest points fall ever on mounting fears of a crippling US recession.

He said McCain was wildly distorting the truth over both Ayers and Acorn, and said voters were turned off by the "100 percent negative" tone taken by the Republican's campaign at a time of rampant economic anxiety.

"John McCain thinks this campaign is all about me — but the truth is, this campaign is about you. Your jobs. Your health care. Your retirement. Your children's future," Obama said in New Hampshire, reprising his debate comments.

"That's what I'm fighting for. Because I can take three more weeks of these attacks from John McCain, but the American people can't take four more years of the same failed policies and the same divisive politics."

AFP