The polls, and more importantly the poll spinners, create the illusion that each presidential candidate already has X percent of the vote and the task, therefore, for John McCain is to try to dislodge some of the Barack Obama voters. That is true, to a certain extent, but it ignores the extraordinary number of voters who haven’t yet decided. From this report :

One in seven, or 14 percent, can’t decide or back a candidate but might switch, according to an Associated Press-Yahoo! News poll of likely voters released Friday.Who are they? They look a lot like the voters who’ve already locked onto a candidate, though they’re more likely to be white and less likely to be liberal. And they disproportionately backed Hillary Rodham Clinton’s failed run for the Democratic nomination.

Fourteen percent?? Isn’t that a lot of voters? Well, yes. And it is especially a lot if the spread on the race is three points (as FOX has it) rather than eleven points (as CBS/New York Times pegs it).

The details on these voters are interesting:

Almost four in 10 persuadables lean toward McCain, and about as many are considering backing Obama, while the rest are either undecided or lean toward other candidates. Viewed another way, about one in every 10 supporters of Obama or McCain says he could still change his mind.

Even so, persuadable voters could be especially fertile hunting ground for McCain in the closing days of a contest in which most polls show him trailing. These people trust Obama less than decided voters do to handle the economy, the Iraq war and terrorism. They are less accepting that the Illinois senator has enough experience to be president. And by a 17 percentage-point spread, more see Republican vice presidential candidate Sarah Palin favorably than unfavorably, unlike the narrow majority of voters already backing a candidate who dislike her.

So the people in play, whose votes McCain most needs, prefer Palin by a 17% spread. That might explain why she is in the state most critical to a McCain upset — Pennsylvania. And these are the people perhaps most amenable to the Joe the Plumber message. Luckily for McCain, that’s most of what he’s talking about these days.

None of this means McCain’s task is easy. But it should remind those certain about the outcome that there are many, many voters who aren’t certain at all about how they are going to vote.