America’s two major political parties have a difficult task: amassing a 51 percent coalition in a nation that has always been — not just now, but from the beginning — regionally, religiously, racially and ethnically diverse.

George W. Bush’s Republicans in 2006 and 2008 were not able to hold together the 51 percent coalition that re-elected him in 2004. Barack Obama’s Democrats in 2014 were not able to hold together the 51 percent coalition that re-elected him in 2012.