Opinion polls show Obama losing ground

As the race for the White House hots up, Republican presidential nominee John McCain has chipped away the lead enjoyed by his Democratic rival Barack Obama, according to the latest average of national polls.

Obama, who hopes to be the first black-American President now holds a three-point lead over the Senator from Arizona, in an average of national polls, 47 per cent to 44 per cent, down from the five-point margin he held over the Vietnam war veteran, television channel CNNs poll of polls says.

The poll of polls includes the latest Gallup daily tracking poll, conducted July 29-31, that showed the two candidates tied at 44 per cent after several days of back-and-forth between their campaigns over the McCain camp's tough new anti-Obama

ad, and accusations of racial politics on the trail.

"It appears that Obama received a temporary boost from his trip to Europe and the Middle East," noted CNN senior political researcher Alan Silverleib. "That boost has now faded, but the overall dynamics of the race have not. Obama is still in the lead as he has been since clinching the Democratic nomination, " Silverleib said.

In addition to the Gallup daily tracking poll, the CNN poll of polls also included a Pew poll conducted July 23-27, a USA Today/Gallup survey conducted July 25-27, and a CNN/Opinion Research Corporation conducted July 27-29.

The CNN poll of polls does not have a margin of error, the network said on its website.