When Michael Bloomberg announced a year ago that he wanted a third term at running New York, a cynic served up the old saw that he was probably the best mayor money could buy.

With a virtually bottomless pit of personal wealth – his estimated $17.5bn (€11.8bn, £10.5bn) fortune makes him the city’s richest man – the two-term mayor seemed guaranteed a hat-trick in a campaign in which he spent about $15,000 an hour to bombard voters with his message of continuity in tough times.