It seems that the GOP is simply better at turning out their voters than the Dems are. In a tossup race, it's usually the side with the better turnout operation that wins it. Other than Obama's two wins, Dems have probably not won the turnout war since 1992 or earlier.
I don't think it is so much about being better at turning them out than it is about Republicans counting some of the highest turnout demographics as part of their base. Old people, the wealthy and well educated are all naturally high turnout voters and also currently Republican-leaning. Meanwhile, Democrats rack up huge margins among minorities and young voters, both of whom generally have some of the lowest turnout rates.
Are the well-educated really Republican-leaning? In Trump's world they're not (not even voters with only a college degree), but even pre-Trump the Republicans did only marginally better with voters with a college degree or more than with voters without a college degree (though it's still very satisying to see George W. Bush win the well-educated voters
). Voters with only a college degree lean Republican while voters with a postgraduate degree lean Democrat, and together they pretty much cancel each other out. Romney got 51% of the college-educated voters and 42% of voters with postgraduate degree, so he got something like 47-48% of well-educated voters in total (probably closer to 48% as there are more voters with only a college education than voters with a postgraduate degree). Though I guess you mean older well-educated voters, and in that case you're absolutely true.
