The Democrats had a good week. When you consider the difficulties that confronted Barack Obama as the party’s convention got under way, the result was something like a triumph. Whether it yields a bounce in support, and for how long, remains to be seen. Unusually, the Republican convention follows almost immediately, and John McCain’s surprising choice of running mate gets it off to an exciting start. The Democrats, it should also be noted, have failed to mend the holes in their policy programme: that work still needs to be done. But they have restored their momentum and Mr Obama has affirmed his authority over the party.

In the days before their convention, Mr Obama’s always slender lead in the polls had narrowed further, and in some John McCain was even edging ahead. Conditions favour the Democrats more than in any recent election. The economy is troubled, living standards are squeezed, house prices are falling. The incumbent administration could hardly be less popular. Going into the convention, the Democrats should have been confident of an easy win in November. Instead they were struggling.