Ezra Klein at The Washington Post says the Bipartisan Policy Center is predicting that the "debt ceiling doomsday" will happen sometime in the second half of February. From there, unless congressional Republicans play nice, it will get ugly:

Imagine we hit the debt ceiling Feb. 15. The BPC’s analysis suggests that federal spending over the next month will be about $450 billion. Federal revenues will be nearer to $277 billion. That means that the government will have to default on about 40 percent of its obligations.

The choices it will face quickly become stark. It can cover interest on the debt, Social Security, Medicare, Medicaid, defense spending, education, food stamps and other low-income transfers, and a handful of other programs, but doing all that will mean defaulting on everything — really, everything — else. The FBI will shut down. The people responsible for tracking down loose nukes will lose their jobs. The prisons won’t operate. The biomedical researchers won’t be funded. The court system will close its doors. The tax refunds won’t go out. The Federal Aviation Administration will go offline. The parks will close. Food safety inspections will cease.

It only gets worse from there. This should be your daily dose of alarmist reading, just so you know how high the debt ceiling stakes could go: Go read the whole thing.