The Post seems to be claiming otherwise in an article that begins with the sentence: "will the U.S. government ever default?" The Washington Post editorial section has been near hysterical in its screaming about budget deficits for most of the last decade. In fact, it was so out of bounds in its rants that it found no space in either its news or opinion section for warnings about the $8 trillion housing bubble. Of course the collapse of this bubble led to the worst economic downturn in 70 years -- and sent the deficit soaring.
It is also worth noting that IMF completely missed the housing bubble and failed to warn of the imminent danger that it posed to the United States and other countries. No one at the IMF was fired over this failure and there has been no major restructuring of its staff, so there is little reason to believe that its understanding of economics is any better or its advice more accurate today than it was in the years before the bubble burst.
Of course the basic hypothesis is silly on its face since the United States issues debt in dollars. It can print as many dollars as it needs to pay off its debt. This could create a risk of inflation, but it rules out the possibility of default. Serious economists and reporters understand this simple point.