Suppose that the economy were to keep growing at 3.5 percent. If that happened, unemployment would eventually start falling — but very, very slowly. The experience of the Clinton era, when the economy grew at an average rate of 3.7 percent for eight years (did you know that?) suggests that at current growth rates we’d be lucky to see the unemployment rate fall by half a percentage point per year, meaning that it would take a decade to return to something like full employment.

Worse yet, it’s far from clear that growth will continue at this rate. The effects of the stimulus will build over time — it’s still likely to create or save a total of around three million jobs — but its peak impact on the growth of G.D.P. (as opposed to its level) is already behind us. Solid growth will continue only if private spending takes up the baton as the effect of the stimulus fades. And so far there’s no sign that this is happening.

So the government needs to do much more. Unfortunately, the political prospects for further action aren’t good.