As the new year turns and Democrats focus on candidates to oppose President Trump in 2020, there’s one number they should keep in mind: 47.
Here’s why. Since the end of World War II, Democrats have elected only four presidents who did not hold the office already: John F. Kennedy in 1960, Jimmy Carter in 1976, Bill Clinton in 1992 and Barack Obama in 2008.
Those four successful Democrats share many t…