The latest memo coming out of Democracy Corps and Greenberg Quinlan Rosner definitively demonstrates both how narrow a ledge Democrats are sitting on in terms of 2012, and the utter volatility of the mood of the electorate. Without a significant improvement in the real economy — by which I mean the economy in terms of how it feels for regular folks and small businesses, not whether Wall Street guys are still getting their bonuses — the smart money would have to be on a sour election for the incumbent President’s party. Since I’m not seeing a significant economic upturn any time soon, you won’t find me whistling past the graveyard and predicting sweeping Democratic victories. However, the raw and unadulterated anger that many voters feel toward both parties, and the extremist positions the entire Republican Party has been forced to embrace by their tea party base, make this a very unpredictable election.

There also are a number of very big variables, each of which could profoundly shake things up. Any of the following three things would clearly have a deep impact on the 2012 election, and all of them in my view are more than 50 percent likely to happen:

1. A European country defaulting on its loans, causing big economic damage to the rest of the worldwide economy.

2. A major bank, either here or in Europe, either going down or needing to be bailed out. And if it happens to any one of them, it could well happen to more.

3. A well-financed (self-financed) third-party candidate running for President.

And while I think it's less than 50-50 that this will happen, I also think that it is entirely possible that the D.C. elites on the supercommittee may end up cutting a deal that delights lobbyists and inside-the-Beltway pundits, but just ends up enraging everyone else — sort of like the lawmakers a couple decades back who were congratulating themselves on their grand bipartisan deal on catastrophic coverage for seniors, but went home to find seniors surrounding and beating on their cars. If the grand bargainers end up cutting things middle-class and senior voters depend on in these tough times, their new Chevy Impalas might end up taking a beating, and the election could get shaken up once again.

A lot of people assume that if any of the above big things happen, Obama and the Democrats will be the ones hurt, but big things happening that shake up the fundamental dynamics of the race aren't necessarily bad if you are a candidate in a tough spot. A wealthy self-funded “centrist” (as defined by the pundits) like Mike Bloomberg jumping into the race would force Obama to his populist left, and that would be a very good thing for him, because when voters are hurting and angry is generally not the best time to run as the most reasonable man in the room. And if a big bank starts to topple, and Obama were to react like he should have done with Citibank in 2009 by taking over and restructuring the bank, and firing the execs, it could show voters that he has learned his lessons and is willing to do the politically tough thing by taking on Wall Street.

When voters are this angry, generally big things happen to change the nature of the election. In 1948, Truman had two splinter groups break from the party, was trashed all year long by the elites, and still won. In 1968, George Wallace did better as a third-party candidate than anyone since Teddy Roosevelt in 1912. In 1980, we had John Anderson, and in 1992 we had Ross Perot — and in both years, the challengers that pundits thought were sure losers earlier in the year were big winners.

One final historical note: the last two Presidents to win when voters were in a bad mood about the economy were FDR in 1936 and Truman in 1948. They ran as strong populists, giving the Republicans and their wealthy benefactors hell. The messaging will have to be right, and so will the policy decisions between now and next fall, but in these volatile times, voters are looking around for someone — anyone — who they think will actually fight for them when the weight of the world is pressed on their shoulders. Obama and the Democrats need to be those kinds of fighters: taking on the banks and the other wealthy special interests, and taking on Republican extremism full-out. If they truly are, as Obama described himself the other day, “warriors for the middle class,” they will have a chance in 2012.