Nate Runs The Numbers

Nate Silver games out not one, but six different scenarios for tomorrow's special election, ranging from a Brown beatdown of Coakley (if all the GOP leaning polls are right) and a 5 out of 6 chance of winning to a Coakley cruise in the most favorable polling scenario giving her a 68% chance of victory.

But the bottom line is he's calling it a coin flip:

To state the obvious, one's assumptions matter a lot! Any of these are reasonable and defensible sets of assumptions. And I'm sure that you some the more creative among you could come up with other wholly reasonable and defensible sets of assumptions, including some that fall outside the goalposts of the scenarios contained herein.

On the heels of the PPP poll, the consensus of other analysts is liable to be that Scott Brown is favored (which I might agree with in the most literal sense), and favored by a large enough margin to characterize the race as something other than a toss-up (which I don't yet agree with.) That's fine; I can see how they get there. The only thing I'd really caution against is that, because our minds are wired to detect patterns, and the story of this race has been Brown! Momentum! Rawwr! it's perhaps easy to forget about some of the polls that did show Coakley ahead, like the Research 2000 poll (which is no less recent than the Suffolk or ARG polls), the Rasmussen poll (at least until they come out with a fresh one), and the Boston Globe/UNH poll, which is definitely old but showed a 17 (!) point lead. It's also easy to forget that all of these polls have their hitches: with the possible exception of Ann Selzer's polling in Iowa, there's no poll anywhere that should be thought of as the gold standard.

In the end, it comes down to Tuesday's vote.  But here's the thing, this has to be the low point so far of Obama's coattails effect.  If Coakley still wins, then the momentum favors the Democrats.  But if Brown wins, it's a breakdown.