Democrat Barack Obama's lead over Republican rival John McCain dipped slightly to five points with three days left in the race for the White House, according to a Reuters poll released yesterday.

Obama leads McCain by 49 per cent to 44 per cent among likely voters in the three-day national tracking poll, down from a seven-point advantage on Friday. The telephone poll has a margin of error of 2.9 percentage points.

McCain, who made solid gains in Friday's single day of polling, sliced Obama's lead among independents from 15 points to six and among women from nine points to four.

"There is no doubt that McCain made some gains," said pollster John Zogby. "It is enough to raise the question, is McCain making a move?"

Obama's support dropped below the 50 per cent mark after two consecutive days at that level. McCain's support has never moved above the 45 per cent mark in the more than three weeks the tracking poll has been taken.

Obama has led McCain in every national opinion poll since late September, and McCain also trails in many of the key battleground states including Ohio, Florida and Pennsylvania. But McCain and his campaign aides say he is clawing back, and McCain enlisted the help of California Governor Arnold Schwarzenegger in the battleground state of Ohio on Friday.

"I know a winning campaign when I see one," McCain said. "We're a couple of points back. Arnold said it best. The Mac is back."

The tracking poll showed Obama still holds an eight-point edge among Catholics and a six-point lead among men. The Illinois senator led among all age groups except those voters between the ages of 30 and 49.

McCain, a former Navy fighter pilot and Vietnam prisoner of war, trails by five points among voters with a member of the military in their family.

The Arizona senator was also winning over only 26 per cent of Hispanics, a fast-growing group that gave President George W. Bush more than 40 per cent of their vote in 2004.

Obama also does a better job of bridging the ideological divide. He is attracting 19 per cent of self-described conservatives, the poll found, while McCain gains only six per cent of liberals.