A clear picture of this divide emerges from the latest Wall Street Journal/NBC News poll, taken in mid-December. Consider:

— Almost 7 in 10 Republican primary voters describe themselves as strong supporters of the traditional definition of marriage as being between a man and a woman. Among Democratic primary voters, the figure is just 25%.

— Among Democratic primary voters, 62% say they strongly back immediate action to combat climate change. Just 13% of Republican primary voters share that view.

— A new issue splitting the parties at their bases is the Black Lives Matter Movement. Almost half of Democratic primary voters call themselves strong supporters of the movement. Only 6% of Republican primary voters do so.

— The National Rifle Association drives one of the biggest wedges of all. Among Republican primary voters, 59% strongly support the NRA, while just 11% of Democratic primary voters are strong backers.