The Gallup daily tracking poll showed Barack Obama and John McCain tied at 44 percent Friday for the third time in two weeks.

McCain has so far been unable to grab the lead from Obama in national polls but he's held the Illinois senator to a narrow advantage. Gallup showed Obama's lead toggling between 2 and 6 points in the first half of August.

McCain is in the middle of an aggressive ad blitz, and has been hammering the theme that Obama is an aloof celebrity in an attempt to gain traction with voters.

Obama's support in the Gallup poll has averaged 47 percent so far in August, while McCain's has averaged 43 percent.

McCain was holding his final all-hands-on-deck strategy meeting with senior staff Friday before the announcement of his running mate and the GOP national convention.