Both presidential campaigns are furiously spinning the scraps of voting data that we now have  -- Mitt Romney's campaign has charts showing President Obama's early edge has fallen off in Iowa, Obama's campaign has photos of long lines at polling stations in several swing states, Romney's campaign is spending money in Pennsylvania. But let's be real. The one state that really matters is Ohio. While it is mathematically possible for both candidates to win without Ohio, it is extremely unlikely. All the last-minute spinning might have left you, dear readers, in a state of confusion about what's going on there. But there's actually a lot we know. To organize our guide to what is happening in Ohio, we're going to take a page from former Secretary of Defense Donald Rumsfeld, who once famously said:

"There are known knowns; there are things we know that we know. There are known unknowns; that is to say there are things that, we now know we don't know. But there are also unknown unknowns — there are things we do not know we don't know."

Known knowns

Why Ohio must be won: The New York Times' Nate Silver's FiveThirtyEight election forecast model shows that Ohio is the state most likely to tip the electoral college vote to one candidate or the other. It holds that Romney has a 3 percent chance of winning without Ohio, while Obama has an 8 percent chance of doing so. A problem for Romney, Silver says, is that for Romney to win without Ohio, he probably needs to pick up Midwestern states that are quite similar to Ohio, like Wisconsin and Iowa. Granted, Silver damaged his credibility in the eyes of the Times public editor with a bet that demonstrated he actually believes his own forecast. But his model relies on the same polls everyone else does.

Official numbers: 1.3 million people have voted -- that's 21.8 percent of the total vote in 2008. Ohio doesn't register by party, but 30 percent of those who've voted last voted in a Democratic primary, while 24 percent last voted in a  Republican one.

Polls: The major poll tracking sites all show an Obama lead in Ohio. Real Clear Politics has Obama is averaging a 2.3-point lead. Talking Points Memo's poll tracker has Obama leading 48.3 percent to 46.8 percent. The Huffinton Post's model shows Obama leading 48.5 percent to 46.1 percent. Drew Linzer's Votamatic shows Obama leading 51.6 percent to 48.4 percent, and forecasts Obama winning 52 percent to 48 percent. Perhaps more important, as you can see in the charts at left, none of these poll trackers has ever shown a Romney lead. Not after the Republican National Convention, not after Romney's great debate performance in Denver.

Known unknowns

Maybe all the polls are wrong? There is a chance that all the polls are wrong. Polling averages did not show Obama winning Indiana in 2008. Polls predicted Senate Majority Leader Harry Reid would lose in 2010, but he's still got his job. That's the case many conservatives are making about Ohio right now. Here's a breakdown of the arguments that the polls are missing something happening on the ground in Ohio:

Maybe we should trust our gut feelings? This is the argument of The New York Times' David Brooks, MSNBC's Joe Scarborough, and The Daily Caller's Matt Lewis, among others: the race feels closer than the polls say. At The National Review, Kevin Holtsberry says he senses something that doesn't show up in the polls, "In my gut this alone tells me Romney will win Ohio. Perhaps I am naïve, but I really believe that most often the better argument wins." But don't just go on one man's gut. Here's another: "I think the intensity is on our side this year... I'm not saying that it isn't close," Ohio Sen. Rob Portman told The Washington Examiner's Byron York. "It is close. But we're not losing. I think it's tied. I do think we've got the momentum on our side."

What about Romney's internal polls? Romney's campaign is reportedly not spinning -- its internal polls actually show something different than the public polls, National Journal's Reid Wilson reports. Republican pollsters think groups that traditionally support Democrats -- people who don't vote often, minorities -- will turn out at a lower rate than the public polls are predicting. "Most of [the public polls] that are outside of one or two points either way oversampled Democrats compared to what we expect this year," Portman told the Examiner. Obama's campaign claims minority turnout is actually going to be higher than some polls forecast. 

Will a better ground game make up for early voting and poll numbers? Karl Rove argues that fewer Democrats requested absentee ballots this year than in 2008, and that about 3,000 more young Republicans have voted early than young Democrats, based on his super PAC's research. He also says the Republican turnout machine is bigger than in 2004. Romney does have 40 field offices in Ohio and has been focusing on its less reliable voters. Obama has 131 field offices. Addisu Demissie, who was Obama's Ohio get-out-the-vote director in 2008, said that Obama is going to build on the voter turnout machine that four years ago not only turned out minority voters in Democratic areas, but turned out black voters in small towns in Republican areas. Obama lost those counties by, in one case, 20 points instead of 30. Obama's heading to one of those small towns Saturday: Lima. In 2004, John Kerry won 84 percent of the black vote in Ohio. In 2008, Obama won 97 percent. The New Republic's Nate Cohn says that if Kerry had only had as many black votes as Obama -- and the white vote stayed the same -- Kerry would have won Ohio.

Unknown unknowns

By definition, we don't know what these are. But let's say they're last-minute dirty tricks: misleading robocalls, misleading mailers, rigged voting machines and the like. Perhaps they could influence the race -- otherwise, why would campaigns pull them year after year?

Unknown knowns

Slavoj Žižek suggests that there's a fourth category, "unknown knowns" -- the things we do not know we know, biases and things like that. For an example of this, we'd point to The Washington Post's Chris Cillizza, who moved Ohio from "lean Obama" to "tossup" on Thursday. Why? Polls show Obama leading by between 1 and 3 points. Plus! "That — coupled with the state’s electoral history and the absolute necessity for Romney to win the state if he wants to be president — leads us to move it back to the 'tossup' category," he writes. But just because Romney needs to win Ohio doesn't mean he has a 50-50 shot of winning Ohio. The things we actually know suggest Obama is likely to win Ohio.