Let's make a crude separation among the voters in any presidential election: those inclined toward the future, the present, and the past. That is, those who want change, stability, or restoration.
The three groups are never even in size. They certainly aren't in this election if the polls are to be believed: change is winning. But naturally a large portion of the electorate will always be leery of change.
In the recent posts here on the internals of the Research 2000 tracking polls, I'm struck by the steepness of the decline in McCain's support among those over 60--traditionally the demographic most inclined to stability. At the end of your earning years, you have every reason to want a stable economy, and a stable income stream. Which is why most investors, as they age, reallocate their portfolios away from stocks and toward low-risk bonds.
John McCain was always going to win the votes of reactionaries; he was always going to lose the change vote; but the basis of McCain's "Obama is unready to lead" argument was always a play for the support of voters who preferred stability to the uncertainty Obama seemed to represent. And yet, since Black Monday and the first presidential debate, the polls have shifted in a way that suggests a remarkable conclusion among these risk-averse voters:
Barack Obama has become the candidate both of change and of stability.
Mindful of this shift (maybe), the new Obama advertising effort to preempt McCain's smear campaign doesn't even try to pre-but the smears themselves. It instead portrays McCain as erratic for changing the focus of his campaign again so dramatically.
Imagine telling George W. Bush in 2000 that his presidency would be so disastrous that afterward millions of swing voters would turn to a 40-something black man with less than four years of major elective office experience in the hopes not of revolution, but of reassurance.