Democrat Barack Obama has 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 on Monday.

Obama leads McCain 50 percent to 44 percent among likely US voters in the latest three-day tracking poll, up from a three-point edge for Obama on Sunday.

The telephone poll has a margin of error of 2.9 percentage points. - Reuters