Blog Posts by David Rothschild, Yahoo! News

Throughout the night, the Signal will be providing updates to our predictions for the presidency and Senate. This is not a real-time tally of results—Yahoo News has that covered—but rather a frequently updated set of our predictions, based on returns, exit polls and prediction markets.

Update, 11:22 p.m.: Obama is not longer virtually certain to win, just certain.

Update, 10:44 p.m.: Obama is virtually certain to win.

Update, 10:10 p.m.: The election continues to break as predicted. As we enter the last stage of the voting, we are waiting to see where FL, VA and OH end up.

Update, 9:50 p.m.: Ohio and Florida are now both strongly pointing toward an Obama victory.

Update, 8:45 p.m.: Only a small fraction of the actual results are in, but what has impressed us so far tonight is how similar the exit polls have tracked with the past few weeks of regular polling. This gives us confidence that the results we have predicted will mainly hold. Heavily leaning states, like Pennsylvania, are going to end up in the Obama column. Florida and Virginia are extremely tight, but as soon as one goes to Obama, if either does, then the election is effectively over. The prediction markets are about 90 percent sure the president will be re-elected heading into the 9 p.m. results.

As liftoff approaches Tuesday evening, the Signal will be focusing (like everyone else) on a small handful of states whose outcomes are not certain or nearly certain well before polls close. Here's a viewer's guide:

The no-drama states

There are 37 states, plus Washington, D.C., who we consider certain for one candidate or another. President Barack Obama controls 14 states and D.C., totaling 186 electoral votes. Gov. Mitt Romney controls 23 states, totaling 190 electoral votes. Virtually every news organization agrees on this list, with only minor variations. The only way Obama or Romney picks off one of these states is if the polls are wildly, wildly wrong and the entire country has shifted dramatically to one side.

The only-a-little-drama states

Seven more states are leaning hard toward one of the candidates (poll closing times in parentheses): Pennsylvania (8 PM ET), Michigan (8 PM and 9 PM ET), Minnesota (9 PM ET), New Mexico (9 PM ET), Wisconsin (9 PM ET), and Nevada (10 PM ET) are leaning heavily toward Obama, for a total of 67 electoral votes. North Carolina (7:30 PM ET), with 15 electoral votes, is leaning heavily toward Romney.

If there are no surprises there, that gets us to 253 electoral votes for Obama and 205 for Romney. Therein lies the central challenge that the Romney campaign has faced since the beginning.

The lots-of-drama states

Six states remain that will probably not be called for hours after the polls close. They are: Virginia (7 PM ET), Ohio (7:30 PM ET), New Hampshire (8 PM ET), Colorado (9 PM ET), and Iowa (10 PM ET) and Florida (7 or 8 PM, depending on county.)

So … who's going to win?

Currently, we predict the following scenarios, each with a certainly likelihood of panning out:

In the last two days, six new polls of Ohio voters have been released, five of which favor President Barack Obama, by leads of 6 points, 4 points, 4 points, 3 points and 2 points. The last reports a tie, from right-leaning Rasmussen, which gave former Gov. Mitt Romney a 2-point advantage last week. Obama now has a 3.1 percentage point lead in Pollster's average for Ohio and a 2.9 percentage point lead in the RealClearPolitics average for Ohio.

A 3 percentage point lead is hardly an insurmountable margin for Obama. But it has been so consistent over the past several weeks that Romney ought to be hoping that the polls favor Obama on a systematic basis by overestimating the turnout of respondents with demographics that favor him. This is certainly possible, but it would mean that many different polling institutions are making similar mistakes. The outcome of Ohio, then, will be as much a referendum on the art of polling as it will be on the art of the presidency.

Sources: Betfair, Intrade, IEM, HuffPost Pollster and RealClearPolitics

Since the final presidential debate, 15 polls have surveyed voter opinion in Ohio, the state that is more likely than any other to determine the election. President Barack Obama leads former Gov. Mitt Romney in 13 of them. The candidates tied in one, and Romney leads in one. Those last two polls were both conducted by Rasmussen, one of the more right-leaning polling institutions, as FiveThirtyEight's Nate Silver has documented.

No one is saying Ohio is a walk for the president. The Huffington Post's Pollster and the RealClearPolitics average both have Obama leading with 51.2 percent among those who express a preference for either major candidate. There is still time for a shift toward Romney, and it's always possible that there is a systematic bias in the polls.

But I don't think it's likely. Historically, polls have been pretty accurate this close to the election. Based only on these surveys, the Signal gives Obama a 75 percent chance of victory in Ohio. When we factor in prediction markets, that figure ticks up a small amount, to 77 percent.

One would think that Gallup, Pew, Rasmussen, every sufficiently wealthy news organization and anyone else interested in conducting a poll would be familiar with the basics of the American electoral system. Why they all insist on continuing to waste precious ink on national polls, then, is completely mystifying.

Gallup's latest poll of registered voters reports that former Gov. Mitt Romney and President Barack Obama are tied nationally, 48 to 48 percent. Gallup's latest poll of likely voters, based on a complex set of assumptions about voter turnout, has Romney leading Obama by 5 percentage points, 51 to 46.

These figures are based on a national sample, so they theoretically include voters from Ohio, Florida and Virginia. They also include voters from Wyoming, California, Alabama, Delaware and about 40 other states whose voters could not possibly be any less relevant to the outcome on Nov. 6.

At this stage in the election, like any sufficiently close election, the fate of the candidates rests with fewer than a half-dozen states. The continuing snapshots of national polls are useful for pollsters and academics, who are interested in things like expected vote share or the probability of victory in the national popular vote. Most stakeholders care only about the likelihood of victory in the Electoral College, and a national poll is not very useful at this point.

This is why most prognosticators consider Obama to have a far higher chance of victory than the national polls would suggest. The Signal has Obama at a 65 percent chance of victory, while Nate Silver gives him a 75 percent chance against Romney. A small, demented chorus of observers has recently dinged Silver for this conclusion, citing various gut feelings to the contrary.

Odds of Obama victory vs. polls

Sources: Betfair, Intrade, IEM, HuffPost's Pollster and RealClearPolitics

If this election is starting to feel interminable, Sunday was an incredible anniversary: Oct. 28, 2012, was the one-year anniversary of the filing date for the New Hampshire primary.

I do not want to sell the election season short. The official campaign began a year ago, but the unofficial campaign began well before that. This time in 2011, Texas Gov. Rick Perry had already flamed out (although his "oops moment" was not until early November) and Herman Cain was dominating the polls.

Most people who run for president appear to have been doing so at least since the third grade—and those are the late bloomers. But even by the bureaucratic measure above, the official campaign to replace President Barack Obama began two years, nine months and eight days after his inauguration. That's 450 days before the next inauguration.

The Republican Party has historically leveraged the subject of abortion far more effectively than Democrats. This year, it could cost them control of the Senate.

The Senate has been up for grabs since the beginning of the cycle. Democrats currently control 53 seats, including the two independents in their caucus, but are defending 23 seats to just 10 on the Republican side. The possibilities are multiplied by uncertainty over who will wield the tie-breaking vote—Vice President Joe Biden or Rep. Paul Ryan—and which party Maine independent Angus King will shack up with in the likely event that he wins.

Two major blows have befallen the Republicans since August. First, Todd Akin's campaign imploded over his statement that women rarely get pregnant from "legitimate rape." Now, Senate candidate Richard Mourdock in Indiana is watching his luck nosedive after stating that "even when life begins in that horrible situation of rape, that it is something that God intended to happen." Under the Signal's prediction model, his odds of victory have plummeted 50 points in 36 hours.

Sources: Betfair, Intrade, HuffPost Pollster, RealClearPolitics

Establishment Republicans did not want either candidate on the ticket in the first place. We considered Indiana a safe Republican hold prior to incumbent Richard Lugar's loss to Mourdock in the primary. Akin knocked off a six-term congressman backed by Sarah Palin in the Missouri primary, to the delight of the Democratic incumbent, Sen. Claire McCaskill.

Monday night was the final set piece of the 2012 election—the last scheduled event in which a significant national audience will tune in to develop or refine their impressions of the candidates. Barring any more secret tapes or raids on high-value terrorists, the remainder of the election is largely outside the candidates' control.

Instant polls of undecided voters after Monday night's debate by CBS, PPP and Xbox/YouGov all declared President Barack Obama the winner in the confrontation with former Gov. Mitt Romney. But the final debate has the smallest chance to make a difference in the election, and the president's performance failed to move the needle in his direction by more than a hair.

Sources: Betfair, Intrade, IEM, HuffPost Pollster and RealClearPolitics

We'll know in a few days how much "Monday Night Football," Game 7 of the National League Championship Series, and Anything-Else-but-a-Foreign-Policy-Lecture detracted from the TV audience Monday night. The Signal does not particularly care about this factor, because the final debate was always destined to have a small impact. Three reasons: