But as other countries’ experiences show, it is also possible that investors would lose confidence abruptly and interest rates on government debt would rise sharply. The exact point at which such a crisis might occur for the United States is unknown, in part because the ratio of federal debt to GDP is climbing into unfamiliar territory and in part because the risk of a crisis is influenced by a number of other factors, including the government’s long-term budget outlook, its near-term borrowing needs, and the health of the economy. When fiscal crises do occur, they often happen during an economic downturn, which amplifies the difficulties of adjusting fiscal policy in response.The most arresting passage in the piece, though, was this one:
According to the Congressional Budget Office’s (CBO’s) projections, federal debt held by the public will stand at 62 percent of GDP at the end of fiscal year 2010, having risen from 36 percent at the end of fiscal year 2007, just before the recession began. In only one other period in U.S. history—during and shortly after World War II—has that figure exceeded 50 percent.The Democrats want to blame Bush for this, but there is an inconvenient truth that they have to ignore to do that: they captured control of congress in the 2006 elections and have had control the purse strings since then.
You can find a link to the document on Greg Mankiw's blog here, or get the document directly here.