In the Washington Post/ABC News poll released earlier this month, white voters prefer Donald Trump in a hypothetical November match-up against Hillary Clinton by 9 points. That's not a huge margin by today's standards, but it probably would have been enough for Gerald Ford to have defeated Jimmy Carter in 1976. Ford lost by 2 points, leading with whites by four, according to exit polling. Had he led by 9, Ford would have won.
But that was 1976, when whites were about 90 percent of the electorate. In 2012, white voters were less than three-quarters of the electorate, as they'll likely be in 2016. And for any Republican, including Donald Trump, a 9-point lead among whites won't be enough.
Former Mitt Romney strategist (and avowed Trump opponent) Stuart Stevens looked at the math for the Daily Beast last week. "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," Stevens wrote. He continued: "The simple truth is that 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."
A few things to notice here. First of all, white voters consistently prefer the Republican Party and non-white voters don't. Or, at least, they don't now that Asian-American voters have switched from backing the Republican (in 1992) to backing the Democrat (since 2000). In 2012, Asian-American voters were even more supportive of Barack Obama than were Hispanic voters.
Also, the percentage of the overall Democratic vote that is from white voters has shrunk over time. In 2012, less than 60 percent of the votes for Barack Obama came from white voters, according to Washington Post analysis -- whereas almost 90 percent of the support for Mitt Romney came from whites. Both parties have seen the share of their support from non-whites increase, but for the Democrats, that increase has been much more substantial.
After Romney's loss, the Republican Party decided to focus on outreach to non-white voters. Stevens' point is that Trump faces unique challenges with outreach to black and Hispanic voters that other Republicans wouldn't.
Because, again: The white vote doesn't go as far as it used to. If you compare the margins of support for the GOP among white voters with the actual results of the election, you can see that clearly. In 1980 and 1988, the Republican candidate received 20 points more support from white voters than did the Democrat. In 1980, the GOP won by 10; in 1988, it won by 8. In 2012, Romney again won whites by 20 points -- and lost by 4 points overall.
In short, then: If Trump does half as well with white voters as did Romney -- and if he's not able to make in-roads with non-white voters, there's simply no way he can win.