(With just one day left before tomorrow’s election, I foresee see five possible scenarios. Each day leading up to Election Day, we have explored one of the scenarios. This post is the fifth and last installment of the series. Tomorrow morning we will predict which one will be the result.)

In a sense, Nate Silver was right all along. The New York Times prognosticator assured us that elections were the sum of their parts. It’s just that he focused on the wrong parts: instead of looking at state races, he should have watched the underlying issues and demographics that were pulling Obama down. The clues were out there: 13% of the President’s 2008 voters in one comprehensive poll defected the Republican way. And there wasn’t much give back from the other side. The “undertow” effect is what some people called it. But after this performance, most just called it (and by exetension, President Obama) “the Big Suck.”

Those expressing enthusiastic support for President Obama had rarely been even within ten points of their enthusiastic opposites who expressed strong disapproval for the incument. With 90% of his base locked up as “broken-glass voters,” Mitt Romney was free to fight for the vital middle ground as early as the first debate. There he increased his lead. Almost every poll leading up to the election found him winning independents by between 6 and 20 points. As Dan McLoughlin noted a week before the race:

“If you averaged Obama’s standing in all the internals, you’d capture a profile of a candidate that looks an awful lot like a whole lot of people who have gone down to defeat in the past, and nearly nobody who has won.”

Meanwhile, in what should have sent up alarm bells across the land, Barack Obama’s campaign was diminished to arguing that it would win on the strength of its get-out-the-vote efforts with youth and minorities. Second to mentioning Harry Truman, this is the last refuge of the losing side. Almost never is depending on sporadic voters a recipe for success. Even in 2008, Obama’s leads with those demographics only padded the margin he had already won because of his eight point lead with independents. Falling precipitously from his earlier indy numbers, he and his acolytes should have known that calamity lay ahead.

Most pollsters took a beating in predicting the race. But that should have been expected too. The last two times that a Republican challenged a Democratic incumbent (1996 and 1980) the polls overestimated Democratic support by 5.1 and 7.2 points. And ’96 was not even in bad economic times.

The biggest gap was not one of gender, but between the opinions of those who voted and those who did not. Those most likely to vote–whites, property owners, investor class, church-goers, married, and the elderly–despised where Obama had taken the country by margins of sometimes more than 20 points. Singles, minorities, and the youth still backed the President, but with diminished support and turnout from four years before.

The entire outcome hinged on who turned out to vote, and when only nine percent of the electorate wished to talk to pollsters, projecting who that was likely to be, became a fool’s errand. But statisticians are not above being fooled. A look at any one of those demographics–even the ones that still supported him–would have showed the President’s downward shift from four years before. But it was too easy to weight bad samples toward a guesstimate of a turnout model instead. Only Gallup got it right, and the result was nasty for Democrats. They went from a 12-point advantage in party identification among likely voters in 2008, to a one-point disadvantage in just four years.

As for the outcome: Romney by 53 to 46. Wave or undertow, it didn’t matter. Barack Obama won only 11 states and DC. They were the few lone blue islands awash in a red sea. The effect downticket was just as bad for Democrats. They returned to the Senate holding only 43 seats (including 2 Independents). Bob Menendez, weighed down by a prostitution scandal, was further hamstrung by a Democratic electorate that, in the wake of Hurricane Sandy, had things to do other than vote while, fooled by the pollsters, they complacently expected a Democratic win. In the House, the GOP returned to Washington with gains and a total of 250 seats.

Gallup was right. A week before the race, early voter polling and actual early voter numbers showed a massive plunge in Democratic support–and this on top of Democratic expectations that they would lose on Election Day but win enough early votes to carry the election. The fall was so dramatic that after the election, Democrats openly contemplated the notion that it was their ideas that were out of touch.

See all the scenarios:

Scenario 1: Nate Silver is right

Scenario 2: RCP is right

Scenario 3: Rasmussen is right

Scenario 4: Gallup tracking poll is right

Scenario 5: Gallup electorate poll is right

And the prediction is . . .