My other alternative scenario was based on the 1980 election, when vast numbers of voters switched from Jimmy Carter to Ronald Reagan after their single debate one week before the election. In that debate, the challenger showed he had presidential stature and the incumbent president seemed petulant and small-minded.
We saw an even more vivid contrast between challenger and incumbent in the Oct. 3 debate. In the next two debates, Obama was definitely more focused and aggressive. But Romney held his own, and post-Oct. 16 polling showed him improving his standing even though many debate watchers thought Obama won on points.
What we may be seeing, as we drink from the fire hose of multiple poll results pouring in, is a slow motion 1980.
The Gallup tracking poll, whose procedure for designating likely voters makes it very susceptible to shifts in the balance of enthusiasm, has been showing Romney ahead by 5 to 7 points.
That suggests that since the Oct. 3 debate Republicans have been consistently more motivated to vote than at least temporarily disheartened Democrats.
That's a factor to keep in mind while assessing polls in old or new target states. Some have samples more Democratic in party identification than in the exit poll in 2008, when Democrats were enthused and Republicans downcast.
The usual caveats are in order. Exogenous events could affect opinion (Libya seems to have hurt Obama). The Obama ground game is formidable. Voters that switched to Romney could switch back again.
And if there is a larger reservoir of potentially changeable voters than in 2004, there was an even larger reservoir back in 1980, when Carter attracted white Southerners who now are firmly in Romney's column.
Mechanical analogies can be misleading. Just because Romney has gained ground since Oct. 3 does not guarantee that he will gain more.
But also keep in mind that Romney gained not just from style but from fundamentals. Most voters dislike Obama's domestic policies and are dissatisfied with the sluggish economy. And now they seem to believe they have an alternative with presidential stature.