Peter Orszag is becoming increasingly honest now that he's no longer the head of the Office of Management and Budget. Here he is on rosy scenarios:
The CBO assumes economic growth will exceed 3 percent per year from 2012 to 2016 before gradually declining to a bit more than 2 percent in 2021. What if, instead, growth remains at 2 percent to 2.5 percent for the next decade? I asked Kogan to recalculate the budget numbers assuming a constant growth rate of 2.25 percent per year, which seems a plausible hard-slog scenario.
He found that the deficit then averages more than 7 percent of GDP. By 2021, it is more than 8.5 percent of GDP and increasing.
Under these modified growth assumptions, the cumulative deficit for the next decade is $13.7 trillion. In other words, the impact from sluggish growth on the budget shortfall over the same period exceeds $2.5 trillion -- which is more than the roughly $2 trillion in deficit reduction that may wind up being agreed to as part of a deal to lift the debt ceiling.
Orszag seems to think that the less favorable outlook is the more likely one.