For what it’s worth, in 1996, when there was an enthusiasm gap between Bill Clinton and Bob Dole, the CNN/USA Today/Gallup poll for Oct. 27-28 gave Clinton a 16-point margin (51%-35%), and the final poll gave him a 13-point margin. Clinton’s actual margin of victory was only 8-1/2 points. So, especially given the much larger enthusiasm gap this year, perhaps there’s reason to hope that the polls contain an even larger overstatement of Barack Obama’s support—in which case John McCain may be ahead. (Yes, yes, I admit that this is wishful thinking.)
I'm not sure about this analysis, but I'm also not sure that the polls in 1996 were as far off as Whelan suggests. StolenThunder lists the following poll results from 1996 which suggests the polling error was much smaller than Whelan suggests:
1996: Actual election results, Clinton 49%, Dole 41%
Zogby: 49-41 Clinton, off by 0.
Gallup: 52-41 Clinton, off by 3.
USA Today: 52-41 Clinton, off by 3.
CNN: 52-41 Clinton, off by 3.
NBC/WSJ: 49-37 Clinton, off by 4.
Harris: 51-39 Clinton, off by 4.
ABC News: 51-39 Clinton, off by 4.
ICR: 51-38 Clinton, off by 5.
Pew: 52-38 Clinton, off by 6.
Battleground: 45-36 Clinton, off by 9.
CBS/NYT: 53-35 Clinton, off by 10.
Just taking a very unscientific approach, lets assume that there was an enthusiasm gap for Dole that resulted in under-polling of Dole support, and that a similar enthusiasm gap exists now for McCain. In 1996, this gap inflated Clinton's lead over Dole by 3.9% on average. Right now, Obama has a lead of 7.3% over McCain in the RealClearPolitics poll average. So even assuming McCain has a similar enthusiasm gap as Dole, it wouldn't be enough to close the gap. Assuming Whelan is correct, McCain must therefore hope that his supporters are extremely unenthusiastic!