Democrat Barack Mr Obamahas expanded his national lead over Republican John McCain in the US presidential race to six percentage points, according to a Reuters/C-SPAN/Zogby poll released yesterday.

Mr Obama leads Mr McCain 50 per cent to 44 per cent among likely US voters in the latest three-day tracking poll, up from 3-point advantage yesterday. The telephone poll has a margin of error of 2.9 per centage points.

The expanding lead for Mr Obama came as he received the endorsement of Republican former Secretary of State Colin Powell and announced he had raised a stunning $150 million in September.

The rally by Mr Obamabroke a string of three consecutive days when McCain had gained ground on the Illinois senator after their final debate on Wednesday. It was the first time in 14 days of the tracking poll that Mr Obamahas reached 50 per cent.

Swing groups

"Mr Obama has really consolidated his base, and now has huge leads among young people, African-Americans and Hispanics," said pollster John Zogby.

"Reaching 50 per cent puts him in winning territory."

Mr Obama also increased his support among two key swing groups that could be vital in the November 4 election. His edge with independents rose from 8 points to 11 points, and his lead among women grew from 6 points to 8 points. Mr McCain narrowly trails Mr Obama among men and leads by 13 points, 53 per cent to 40 per cent, among whites.

"McCain seems to have slipped a little bit, but in the grand scheme it’s still a very close race," Zogby said. Mr Obama has led Mr McCain, an Arizona senator, by between two and six points in all 14 days of polling. "This race has not really moved all that much in two weeks," Zogby said.

His fundraising haul shattered the records he already owns and will fuel a huge advantage for Mr Obama in paid advertising in the final 15 days of the campaign.