The enormity of the task that lies ahead
What’s the problem? The problem is the word enormity, which has a primary sense of monstrosity or outrage. Most careful writers avoid using it to mean immensity (see usage notes here and here), although it is that sense (a common one where unselfconscious and less-skilled writers are involved) that I think Obama intended.
Then again, maybe he looked at the ugliness of the current financial and economic crisis and decided that enormity was le mot juste after all.