Washington, Oct 28 : Democratic presidential nominee Barack Obama is leading in virtually every national poll, but his margin fluctuates wildly -- suggesting that in some cases, the numbers do in fact lie.

Obama has been leading his rival John McCain in almost every national poll since late September, and it may seem like he’s got the election all sewn up.

But the Democratic presidential nominee’s margin has fluctuated wildly, anywhere from 1 to 13 points in the past two weeks alone. And a few recent polls are even within the margin of error, suggesting McCain could actually be leading among certain sets of voters.

This doesn’t mean the surveys are masking a widespread McCain advantage – he’s still trailing in most major battlegrounds needed to secure the election. But survey disparities are so great this year as to suggest that the numbers, contrary to the old adage, sometimes do lie.

FOX News political analyst Karl Rove said by his count, there have been 177 national polls conducted as of October 24, compared with 55 at the same time in 2004.

“The proliferation of polls, particularly polls run by universities that may not have the skill and capability that a professional polling outfit has, are really not helpful to the process, in my opinion,” Rove said.

But some of the inconsistencies in the polls this year can also be traced to the method used by the pollsters.

The “expanded” Gallup poll, unlike the “traditional” one, includes those citizens who call themselves likely voters but who’ve never actually voted before.

“This year, I think all pollsters are concerned about how they''re defining likely voters, and trying to understand turnout,” FOX News polling director Dana Blanton said.

Obama held a 10-point lead Monday in Gallup’s expanded poll, but only a 5-point lead in their traditional poll.

Karlyn Bowman, who studies public opinion for the American Enterprise Institute, urged voters to examine the wording and sequencing of a poll''s questions, to be wary of sudden spikes -- and to shop around.

A survey of the polling landscape shows the latest CBS News/New York Times poll to be the outlier, placing Obama up by 13 points.

A FOX News/Opinion Dynamics Poll last week had Obama up by 9 points.

Investor''s Business Daily, which came closest to nailing the race between President Bush and John Kerry in 2004 (within four-tenths of a point), has the current presidential race within the margin of error. And The Associated Press recently reported a virtual tie. (ANI)