That there is so much conviction that it might be easy for Republicans to win a national election is an odd one given history. Over the last six presidential elections, Democrats have won 16 states every time for a total of 242 electoral votes out of the 270 needed to win. In those same six elections, Republican presidential candidates carried 13 states for 103 electoral votes. Here’s another way to look at it: the last time a Republican presidential candidate won with enough votes to be declared the winner on election night was 1988.

In 1980, Ronald Reagan won 56 percent of white voters and won a landslide victory of 44 states. In 2012, Mitt Romney won 59 percent of whites and lost with 24 states. But it’s a frequent talking point that white voter enthusiasm was higher for Reagan and turnout down for Romney. Not so. In 1980, 59 percent of whites voted and in 2012, 64 percent of whites voted.

But still the myth survives that there are these masses of untapped white voters just waiting for the right candidate. Call it the Lost Tribes of the Amazon theory: If only you paddle far enough up the river and bang the drum loud enough, these previously hidden voters will gather to the river’s edge. The simple truth is that in there simply aren’t enough white voters in the America of 2016 to win a national election without also getting a substantial share of the non-white vote. Romney won 17 percent of the non-white vote. Depending on white voter turnout, a Republican needs between 25 percent and 35 percent of the non-white vote to win. RealClearPolitics has a handy tool so you can play with the percentages: