The answer, obviously, is just one but they must be certain they can change the lightbulb come 2020 and that’s why they need a year-long nomination process and 12 primary debates, moderated according to strict time controls, with candidates drawn from lots in a live CNN draw, and the whole thing aired on the same “partner” network, which starts coverage about 18 hours before the debate begins, with suitable countdown clocks, choirs, speeches, pre-debate rituals, introductions, handshakes, honour guards, presentation of colours, anthems and then, before anybody can actually speak, another quick message from our sponsors…