Felix Salmon argues that the country isn't in risk of default:

for all the rhetoric from campaigners about countries struggling under their debt burdens, there really isn’t much of a correlation between the level of a country’s debt and the probability that it’s going to default especially not when that debt is wholly denominated in domestic currency. Countries with low debt-to-GDP ratios can default just look at Ecuador right now while countries with very high debt-to-GDP ratios can stay current on that debt indefinitely Japan is the most obvious example, but there are many more.
If you want to come up with a scenario where a developed country defaults on its debt, you’re most likely to look at a case like Italy, where the debt is denominated in euros and there’s a non-zero chance that the country is forced out of the eurozone; in general, if you want a sovereign default, the best way to get one is to find a country with hard-currency borrowings which then has a massive devaluation. That can’t happen in the US there’s no currency mismatch between its tax revenues and its liabilities.