Late yesterday, Gallup came out with new numbers on the generic ballot question—which party’s candidates would you vote for in the election for House of Representatives? Among registered voters Gallup shows Republicans ahead by 46%-42%, about as good a score as Republicans have ever had (and about as bad a score as Democrats have ever had) since Gallup started asking the question in 1942. However, Gallup also shows the results for two different turnout models. Under its “high turnout model” Republicans lead 53%-40%. Under its “low turnout model” Republicans lead 56%-38%. These two numbers, if translated into popular votes in...