If there were some kind of run-off provision, Todd Akin would not have been the Republicans’ Senate nominee in 2012: Either of his rivals would have beaten him in a one-on-one race. That Republican would almost certainly have then won the seat.

In West Virginia, too, it seems likely that Morrisey or Jenkins would be able to beat Blankenship in a one-on-one race, or at least that the inability of people who don’t want Blankenship to pick one candidate has made it much more likely that he will win. (Facilitating that kind of co-ordination is one of the things party establishments used to be for, but I digress.)

This isn’t a foolproof way to avoid bad candidates: Moore won a run-off in Alabama. But I think it would help.