It’s no secret that Republicans have a demographic problem when it comes to national elections. But what many people don’t realize is that the GOP’s issues will be worse in 2020 than in 2016 — unless things change dramatically.

Consider this: In 2012, roughly nine out of every 10 people who voted for Mitt Romney were white — even as the white vote continued its steady decline as a percentage of the overall electorate. Romney lost African American voters by 87 points and Hispanics by 44 points.

In an essay in Commentary magazine on the demographic problem his party faces, former Bush administration official Pete Wehner writes:

“It’s an undeniable empirical truth that the GOP coalition is shrinking, and it’s shrinking in the aftermath of two fairly decisive defeats, with the latter coming against a president whose policies were judged by many Americans to have been failures. Which means the Republican task isn’t simply to nominate a candidate who can fire up the base; it is to find principled conservative leaders who can win over voters who are not now voting for the GOP at the presidential level.”

It’s a problem for Republicans as they face the prospect of a jam-packed 2016 presidential field, in which the fissures between the GOP’s establishment and tea party wings are likely to be on full display. And there’s every reason to believe it’s only going to get worse: The 2016 election will be a tough one for Republicans to win, given the demographic changes in the United States, but it may not be nearly as difficult for them as the 2024 or 2028 election could be.

A new study from the Carsey Institute, a nonpartisan public policy think tank housed at the University of New Hampshire, proves that point.

Using data from the 2012 census, the report showcases just how fast the minority population is growing among Americans younger than 20, even as growth in that same age group among whites is basically stagnant. The study’s authors write: “In 1990, 32 percent of the population younger than age 20 was minority, increasing to 39 percent in 2000. By July of 2012, 47 percent of the 82.5 million people under age 20 in America were from minority populations.”

What that means is that Americans younger than 20 are significantly more diverse than the rest of the population. While minorities make up 47 percent of the younger-than-20 population, they are just 33 percent of the older-than-20 population.

The math isn’t complicated. Winning 27 percent of the Hispanic vote and 6 percent of the African American vote — as Romney did in 2012 — makes it hard to win a majority of the overall vote when those groups represent 10 percent and 13 percent of the electorate, respectively. If Hispanics increase to 20 percent of the electorate by 2024 or 2028, and the Republican presidential nominee’s performance is roughly equivalent to Romney’s 2012 showing, it will be impossible — or close to impossible — for that GOP nominee to win a national majority.

And it’s not just the raw numbers that should concern Republicans. It’s where the younger-than-20 minority populations live that could prove politically problematic.

The concentration of young minorities in the Southwest and the South means that states such as Texas, Arizona, Georgia and South Carolina — which have all been conservative redoubts at the presidential level for decades — could be in real jeopardy for the GOP in the medium and long term.

Now, party politics tend to work like a pendulum. In the 1980s, it looked like Democrats would never again come close to securing the 270 electoral college votes they needed to win the presidency. The idea of a Republican-controlled House was long considered laughable by political sharps. So making assumptions about what the two parties will look like in eight or 12 years is, by its very nature, somewhat unreliable.

But, as of today, Republicans have a demographic problem. And it is going to get much, much worse unless they find a way to improve their numbers among Hispanics and, to a lesser extent, African Americans. And they need to figure it out fast.

To read previous Monday Fix columns, visit postpolitics.com.