The Gallup Poll Daily tracking from Oct. 2-4 found 50 percent of those surveyed said they supported Obama, while 43 percent preferred McCain, Gallup said Sunday on its Web site.

It was the ninth consecutive day the tracking poll showed Obama ahead by a substantial margin, tying his previous record as a Gallup front-runner, set in late August and early September, about the time of the Democratic National Convention.

The survey result released Sunday reflected two full days of polling following Thursday's vice presidential debate between Obama's running mate, U.S. Sen. Joe Biden of Delaware, and McCain's running mate, Alaska Gov. Sarah Palin.

The poll, conducted by land-line telephone and cell phone, was based on a sample of 2,728 registered voters and has a margin of error of 2 percentage points.