The ongoing economic crisis and President George W. Bush's unpopularity at home and abroad have made it "difficult" for any Republican candidate to win the White House, a former spokesperson for John McCain said Sunday.

Todd Harris, McCain's spokesperson during the 2000 campaign battle for the Republican presidential nomination, said few candidates would have been able to dig out from under the shadow of Bush's low approval ratings, now hovering around 25 per cent.

"John McCain, believe it or not, is probably the best candidate that we could have put forward because of his long history as an independent maverick who is willing to take on his own party," Harris said during an interview on CTV's Question Period. "But in this environment, it would have been difficult for any Republican."

Harris would not speculate on what the McCain campaign could have done differently to prevent Obama from pulling ahead in the polls. An Associated Press-Yahoo News national poll of likely voters released Sunday showed Obama ahead 51 per cent to 43 per cent, with a margin of error of plus or minus 3 percentage points.

Harris conceded that it will be "very, very difficult" for McCain to win this Tuesday.

"It's not impossible and you should never count anyone out, particularly John McCain, with two days still left," Harris said. "But it's an extremely, extremely difficult climb for him right now."

Harris went so far as to suggest that should McCain lose Tuesday's election, "he will be the first to say that he has lived through much, much worse than this. The things that he has survived, five-and-a-half years in a POW camp, are far bigger challenges than simply losing an election."

Whoever wins, this election is one of the most closely watched in recent memory, Harris said, and the inclusion of Obama on the ticket has generated a great deal of goodwill toward the United States.

"I have to say, even for someone who's not an Obama supporter, it's nice to have the world looking at the United States again without the level of disdain that they've had for the last eight years," Harris said. "And I think that ultimately that's actually good, not only for America's national security, but for national security all across the world."