The talk of the political world today — aside from the headshaking effort to blame McCain and Palin for some people yelling in their crowds against Obama and asking McCain wild questions — is the interesting admission by the Gallup Organization that it is having great trouble understanding what is going on in this year’s election. Gallup acknowledged today that ithas criteria according to which a) Obama and McCain are separated by 4 points, b) they’re separated by 6 points, and c) they’re separated by 7 points.

What’s most interesting is that, according to the criteria Gallup would ordinarily use, the contest has a four-point spread, 50-46 in Obama’s favor:

Obama’s current advantage is slightly less when estimating the preferences of likely voters, which Gallup will begin reporting on a regular basis between now and the election. Gallup is providing two likely voter estimates to take into account different turnout scenarios.

The first likely voter model is based on Gallup’s traditional likely voter assumptions, which determine respondents’ likelihood to vote based on how they answer questions about their current voting intention and past voting behavior. According to this model, Obama’s advantage over McCain is 50% to 46% in Oct. 9-11 tracking data.

The second likely voter estimate is a variation on the traditional model, but is only based on respondents’ current voting intention. This model would take into account increased voter registration this year and possibly higher turnout among groups that are traditionally less likely to vote, such as young adults and racial minorities (Gallup will continue to monitor and report on turnout indicators by subgroup between now and the election). According to this second likely voter model, Obama has a 51% to 45% lead over McCain.

The 7 point spread, 50-43, is among American adults who are not asked whether or not they are likely to vote.

Other pollsters, Scott Rasmussen primarily, have bet on a very significant swing to Democrats between 2004 and 2008 among likely voters and are “weighting” their results to reflect it.

There are two presumptions at work in Gallup’s decision to offer two different “likely voter” scenarios. One is that the electorate in 2008 will act the way electorates have in the past, with very little exceptions. Republicans will come home to the GOP candidate; Democrats will vote for the Democrat; independents will break a little bit for one or the other, and will decide the election. Michael Barone, in 2004, said the conduct of independents had turned America from the 50-50 nation it was in the 2000 election to a 51-49 electorate that favored Republicans.

In 2006 — not exactly an election from which one can easily extrapolate, because it was a midterm and the electorate was far smaller than it will be this year — Republican voters stayed home, independents broke for the Democrats, and the overall partisan vote tally was a landslide 53-46 for the Democrats.

The second “likely voter” scenario suggests the 2006 election was a harbinger — brilliant get-out-the-vote efforts by Democrats, who had more money than Croesus, and independents deeply soured on the GOP because of the Iraq war and corruption. Those voters who went Democrat, especially the independents, will stay Democrat, according to this theory.

Add to this the common conviction that Obama will score northward of 95 percent of the black vote, which will turn out in record numbers. Then add to that the notion that Obama appeals to younger voters to such a degree that they will actually turn out on Election Day, which they largely don’t do even if they are registered. And what you get is an electorate very favorably disposed towards the Obama ticket.

The poll numbers universally agree that Obama is ahead. But the polls that suggest he has put the election away are relying on the notion of an electorate that is now tilted significantly to the Democratic side. What if that notion is overblown? After all, Obama spent the spring underperforming in polls against Hillary Clinton, demonstrating that his vast appeal to youth didn’t mean youth would actually bother to show up in sufficient numbers to let him finish her off.

The truth is, nobody knows. I think the last week of the election will offer hard evidence of whether McCain has lost the independents, and, therefore, the election. Until then, though, despite the conventional wisdom that it’s all over, McCain clearly has some kind of way to win this. Don’t ask me what it is, but even after this horrific week, Obama hasn’t yet closed the sale.

Or, at least, that’s what the polls say. Why should we listen to them? They’re all telling us they have no idea what the electorate looks like.