Is it even possible for John McCain to "win," credibly?

With so many national and statewide polls pointing to an Obama victory (and likely landslide), would a “win” by McCain be viewed so skeptically by the American people as to be incredible?

I am aware of the history with Truman and Dewey, for those itching to bring that up. Back then however, pre-election polls were not so emphasized, nor did the media glare shine so brightly as it does today.