The South Dakota Senate race is Schrödinger's election

All eyes are now turning to to South Dakota, as what was long thought to be an easy win for Republican Mike Rounds is suddenly a messy three-way race with a fourth candidate yapping along behind them all.

So what do we know about the state of the race in South Dakota? The polls.

This is a race in flux, so we should only use the most recent polls. And Nate Cohn of the New York Times tells us we should exclude the CBS/NYT/YouGov poll of the race. That leaves three polls; averaged together, the margin has Rounds ahead of Democrat Rick Weiland by 9.

Now I'd like to introduce one more known unknown: Polling averages in contests like this one usually fail, sometimes spectacularly.There is a very good chance the actual state of the race is much closer than the polls say. To be fair, there is also a very good chance the opposite is true as well.

There's currently three recent polls and four candidates for SD-Sen. Below, I've tallied up all the errors of polling averages (averages of the D-R margin) in races like this one since 2004, where the major parties together had less than 95 percent of the vote, and three or more polls in the polling average:

The dark bar in the middle is the zero point, where polling averages were essentially correct. On the left, races where the margin in the polls was too Republican compared to the results; on the right, the margin in the polls was too Democratic compared to the results.

One thing that's for certain is Rick Weiland needs our help. Please contribute $3 today.

Voting by mail is convenient, easy, and defeats the best of the GOP's voter suppression efforts. Sign up here to check eligibility and vote by mail, then get your friends, family, and coworkers to sign up as well.

Head below the fold to learn more about just how uncertain things are in South Dakota.