Republican John McCain heads into the final stretch of the US presidential campaign with a 4-point lead over Democrat Barack Obama, a USA Today/Gallup poll released on Sunday showed.

The lead was McCain's biggest since January and a turnaround from a USA Today poll taken just before last week's Republican Party convention opened, when the veteran Arizona senator trailed Obama by 7 percentage points.

The new poll, taken Friday through Sunday, showed McCain leading Obama, a first-term senator from Illinois, by 50 percent to 46 percent among registered voters with less than two months before the Nov 4 election.