The American Congressional Budget Office (the inspiration for our own Office of Budget Responsibility) has released a report warning that the impact of the upcoming "fiscal cliff" would be to wipe 4 per cent from GDP growth for 2013.
The fiscal cliff – a phrase coined by federal reserve chairman Ben Bernanke – is the result of a series of several major budget provisions all expiring at once, at the same time as some of the automatic cuts negotiated as part of the debt ceiling crisis last summer come into effect, and several tax cuts time out. More broadly, though, it is the result of America's frankly broken political system.
In March, Congress failed to pass  two potential measures which would have ended the crisis:
The first, a bipartisan bill which has the most chance of passing in the Democrat-controlled Senate, was defeated 382-38; the second, the White House's preferred option, was unanimously rejected 414 to 0.
If something is not passed by the time the various provisions expire, on 31 December, then the CBO estimates that:
Those policies will reduce the federal budget deficit by $607 billion, or 4.0 percent of gross domestic product (GDP), between fiscal years 2012 and 2013. The resulting weakening of the economy will lower taxable incomes and raise unemployment, generating a reduction in tax revenues and an increase in spending on such items as unemployment insurance. With that economic feedback incorporated, the deficit will drop by $560 billion between fiscal years 2012 and 2013, CBO projects.
If all the fiscal blows are deflected, the economy should grow by 5.3 per cent (annualised) in the first half of next year. If they aren't, it will instead contract by 1.3 per cent.
The coming showdown has been compared by many to the debt ceiling crisis, when Congress hit deadlock last summer over a budgetary provision which would have caused America to default on its debt, but in many ways, it is more dangerous still. The debt ceiling itself will reenter the political battleground in spring of 2013, and the Republican leader John Boehner is signalling  that he will play hardball over the issue. Then there's the fact that the deal will be happening shortly after the presidential election so there is no incentive for dealmaking to start until November; both parties' incentives will differ greatly depending on who will be inheriting the mess.
Related, Joe Weisenthal suggests  the most apocalyptic scenario possible:
It's very easy to imagine Romney winning the popular vote and Barack Obama winning the electoral college. In fact, the electoral college map is VERY favorable to Obama. This scenario is definitely possible and it would be the fiscal cliff Black Swan.
If you thought Congressional Republicans were going to be intransigent on the debt ceiling, multiply that by 10x. Any goodwill would be dead as the Republicans would feel a mandate based on the desires of the majority of the people, and Obama would be weak.
It would be NUTS!