Democrats look for that old debate magic – but can anyone defeat Trump?

As he sensed the crowd flagging, Donald Trump switched gears to the all-important question of his re-election slogan. Should the insurgent turned incumbent stick with “Make America great again” (Maga), which he characterised as “probably and possibly the greatest theme in the history of politics”? Or should he switch to “Keep America great”?

It was the latter that that turned the stadium into a cauldron of noise.

“Ah, I’m sorry, Maga Country, but that wasn’t too close,” the president said on Tuesday night. “I thought you had it won, and...