Were he facing a more charismatic candidate than Mitt Romney or a less extremist bunch than the Republicans, Mr Obama would already be staring at defeat. The fact that the president has had to “go negative” so early and so relentlessly shows how badly he needs the election to be about Mr Romney’s weaknesses rather than his own achievements. A man who four years ago epitomised hope will arrive in Charlotte with a campaign that thus far has been about invoking fear.

Mr Obama must offer more than this, for three reasons. First, a negative campaign may well fail. The Republicans are a rum bunch with a wooden leader; but Mr Romney’s record as an executive and governor is impressive, and his running-mate, Paul Ryan, is a fount of bold ideas. Mr Obama’s strategy of blaming everything on Republican obstructionism will strike many voters as demeaning. …

Second, even if negative campaigning works, a re-elected Mr Obama will need the strength that comes from a convincing agenda. Otherwise the Republicans, who will control the House and possibly the Senate too, will make mincemeat of him. And, third, it is not just Mr Obama who needs a plan. America does too. Its finances and its government require a drastic overhaul. Surely this charismatic, thoughtful man has more ideas about what must be done than he has so far let on?