But their leftish policies, in Clinton’s first two years and Barack Obama’s two terms, have helped produce Republican majorities in nine of the next House elections and have resulted in the polarization of the electorate that so many pundits lament — and which is the last thing Perot promised.

What could be the consequences of a third-party Trump candidacy? Immediate speculation is that it would cost Republicans the votes of many conservatives disgruntled with the party’s officeholders and angry about immigration, trade, and Common Core. That’s certainly plausible.

But Trump might also siphon votes of non-college whites from Democrats in states where their support was high enough to produce Obama victories. Examples include Iowa, New Hampshire, Colorado, Nevada, New Mexico, Ohio, Michigan, Wisconsin, and Minnesota. All voted 54 percent or less for Obama in 2012, and altogether they have 84 electoral votes.