The Republican campaign has turned highly personal over the past week asking "who is the real Barack Obama" and suggesting that he was not candid or truthful.
That attack came on the back of a speech by Sarah Palin, McCain's running mate, in which she accused the Democrat of "palling around with terrorists".
During rallies after the initial attacks, Republican supporters shouted "traitor," "terrorist," "treason," "liar" and even "off with his head," in reference to Obama.
McCain was still trailing Obama by four per cent in a Reuters/C-SPAN/Zogby tracking poll released on Monday. While a Washington Post-ABC News survey gave the Democrat a lead of 53 per cent to 43 per cent over his rival.
"He [McCain] doesn't need an attack strategy, he needs a comeback strategy,'' Alex Castellanos, a longtime national Republican media consultant who worked for Mitt Romney's campaign for the nomination, said.
There were signs as early as Friday that the negative tone was not having the desired effect. McCain drew jeers at a town hall meeting in Minnesota when he defended Obama after a supporter said he feared what would happen if Obama were elected president.
He also cut short a woman who described Obama as an Arab, saying his rival was "a decent, family man".
'Seeds of hatred'
The strategy had drawn a stinging rebuke from John Lewis, a highly respected veteran of the civil rights movement and a Democratic congressman, comparing the remarks to the atmosphere fostered by George Wallace, a segregationist governor, in Alabama in the 1960s.
In a statement issued on Saturday, Lewis said McCain and Palin were "sowing the seeds of hatred and division, and there is no need for this hostility in our political discourse".
McCain rejected any comparison to Wallace.
"I am saddened that John Lewis, a man I've always admired, would make such a brazen and baseless attack on my character and the character of the thousands of hardworking Americans who come to our events," he said.
Obama and McCain will meet on Wednesday in their third and final debate before the Novemebr 4 election, with the Republican candidate vowing to "whip" Obama.
"We're a couple points down, OK, nationally, but we're right in this game," he told the campaign workers in Virginia. "I know that we're going to win this race."
McCain has been hurt by the perception of many voters that Obama would be better at handling the current global economic crisis, the issue that has overtaken all others on the campaign trail.