Imagine an autopsy that concludes the cause of death was a drug overdose. After the funeral, distraught family members assemble to talk about how they could have prevented such a senseless tragedy. Then, after brief reflection, they all decide to start mainlining heroin.

That, in a nutshell, is the history of the Republican Party over the past half-century.

The GOP is addicted to whiteness, a psychological drug it started ingesting in the early 1960s with the encouragement of Goldwater conservatives, who argued that the party could win over the traditionally Democratic white South by resisting the civil rights movement. Richard Nixon was one of the Republicans who initially had trepidations. “If Goldwater wins his fight,” he told Ebony magazine in 1962, “our party would eventually become the first major all-white political party. And that isn’t good. That would be a violation of GOP principles.”

Nixon was right. But like most party leaders, he soon came around to the Southern Strategy, crafting a set of coded appeals to white resentment that helped him win the White House in 1968 and 1972. If Goldwater was the GOP’s original dealer, Nixon was its first full-blown junkie.

Like any decent recreational drug, whiteness initially made the Republican Party feel good. It fueled a swing to the right that picked up many disaffected whites unhappy with the Democrats’ embrace of civil rights. Following Nixon, it powered the national victories of Ronald Reagan and the George Bushes. But over time, the very drug that made the Republican Party so powerful slowly started to kill it.

The way Barack Obama won in 2008 left Republicans feeling jittery about the future. Obama’s victorious coalition was built not only on a record turnout of African American voters, but also on overwhelming support from Latinos, Asian Americans, and other nonwhites. He won three big Southern states—Virginia, North Carolina, and Florida—without pandering to conservative whites. And the groups that fueled his victory were increasing rapidly as a share of the electorate.

Yet even as Republican leaders recognized the damage whiteness was doing to the party, they couldn’t give it up. They’d grown so accustomed to relying on the stuff that it was impossible to imagine life without it. Sure, they made a few half-hearted attempts to kick the habit. They tried reaching out to minorities—think Jack Kemp’s “enterprise zones” for distressed urban neighborhoods, or George W. Bush’s faith-based initiatives, which channeled federal funds to black churches. And they held up a succession of figures—from Alan Keyes and J.C. Watts to Herman Cain and Ben Carson—as model black Republicans. But such efforts always carried a whiff of desperation. The party wasn’t changing its core policies and messages. It was just slapping a “postracial” patina over its fundamental whiteness.

Not long after Mitt Romney’s defeat in 2012, Republican National Committee chairman Reince Priebus convened party notables to conduct what was informally described as an “autopsy.” The resulting set of recommendations had a bland and euphemistic title: “Growth and Opportunity Project.” But the autopsy itself was unusually blunt: The GOP lost the 2012 presidential election because it had alienated young people and nonwhites. And in the future, the party’s whiteness would “tilt the playing field even more in the Democratic direction.” Between 1980 and 2012, the autopsy noted, the white share of the electorate had plunged from 88 percent to 72 percent—a trend that would only accelerate.

The autopsy paid special attention to Hispanic voters, whom Romney had turned off in droves by championing “self-deportation.” The RNC urged a dramatic remedy: Get behind comprehensive immigration reform.

Instead, Republicans responded by doing the exact opposite. After a brief interlude in 2013, when Senate Republicans in the so-called Gang of Eight joined Democratic colleagues to try and forge an immigration deal, the party faced a grassroots revolt and backed away from reform, stifling the measure in the House of Representatives.

The most notable about-face came from the senator who seemed to embody the party’s best hope for recovery. Young, Latino, and wired into popular culture, Marco Rubio helped negotiate the original immigration deal, then distanced himself from the measure after being stung by blistering nativist attacks from right-wing sites like Breitbart, which ran scare items claiming that undocumented migrants would be given free cell phones (dubbed “MarcoPhones”). Yet Rubio’s willingness to betray immigration reform didn’t help him with white voters: When he ran for president, many conservatives shunned him.

Rubio’s dilemma over immigration was a microcosm of the Republican Party’s larger problem with race. Any move to make the party more inclusive precipitates an uproar from its overwhelmingly white base, which remains committed to stopping the very demographic changes the party needs to embrace. So rather than conquer its addiction to whiteness, the GOP has responded to the dwindling supply of white voters by shooting up even faster, desperate to enjoy the high while it still lasts. The party’s first response to Obama was the rise of the Tea Party, a nakedly nativist appeal to white unity. Now Republicans have doubled down by turning to Donald Trump, a presidential nominee far more openly racist than any national politician since the heyday of George Wallace.

Consider how much worse the GOP’s whiteness addiction has grown in just the past four years. Mitt Romney was a powder-cocaine Republican, a socially acceptable xenophobe offering a high that made whites feel like masters of the universe: Still in charge here! Trump, by contrast, is dealing meth—a trailer-park drug you take when you’ve given up hope and just want to get rip-roaring stoned. Compared to the country-club slickness of Romney’s cocaine conservatism, Trump’s meth-head politics are at least more honest. Instead of Nixonian euphemisms about law and order, or Reaganite winks about welfare queens, Trump offers the intoxicating thrill of telling protesters and immigrants—them—to get the hell out. It’s an intense high. And the aftermath will be tooth-rottingly ugly.

One reason Republicans so fiercely resist change is that they’ve developed a complicated mythology of denial that winds around to a skewed conclusion: The party doesn’t need to focus on nonwhite voters, because the real problem is that white conservatives are sitting out elections. After Romney’s loss, this thinking was given its most sophisticated form by Sean Trende of Real Clear Politics, who argued that the defeat was the result of five to seven million “missing white voters.”

As political scientist Ruy Teixeira has shown, Trende’s theory rests on shaky ground, since voting by nonwhites declined in 2012 at roughly the same rate as voting by whites. Besides, the true “missing” voters are Asian Americans and Latinos, who go to the polls at a lower rate than whites or blacks (though Trump’s presence on the ballot could change that in November).

But as dubious as Trende’s notion of missing white voters may be, it speaks to a powerful longing in the Republican Party to avoid changing its core policies to appeal to a broader swath of American voters. When the GOP autopsy was released in March 2013, it immediately received a harsh rebuke from talk radio’s kingpin of whiteness. “They think they’ve gotta rebrand, and it’s all predictable,” Rush Limbaugh told his millions of listeners. “They gotta reach out to minorities, they gotta moderate their tone here and moderate their tone there. Nonsense. The Republican Party lost because it’s not conservative. It didn’t get its base out in the 2012 election.”

Versions of the “missing white voters” theory were put forward by both of the leading Republican candidates this year. Ted Cruz claimed that he would get millions of votes from evangelical conservatives who felt betrayed by mainstream Republicans. Trump, meanwhile, has boasted that he will attract the support of vast numbers of disaffected voters, most of them working-class whites. Cruz’s claim was soundly debunked during the primaries; Trump’s has yet to be tested beyond the narrow bounds of the GOP base.

More recently, Limbaugh has been spinning a whole new take on the mythology of Republican denial: the idea that minorities actually adore Trump. This theory ignores every national poll, focusing instead on the backing Trump received from the vanishingly few nonwhite voters during the GOP primaries. But that’s enough for Limbaugh. So the RNC wants to build a broad coalition? “Guess who’s doing it?” Limbaugh proclaimed in March. “Donald Trump is doing it! Donald Trump has put together a coalition—whether he knows it or not, whether he intended to or not—he’s put together a coalition that’s exactly what the Republican Party says that it needs to win!”

It’s well known that Limbaugh once wrestled with OxyContin abuse. But his suggestion that Trump will help the Republican Party gain nonwhite voters sounds like the product of far more powerful hallucinogens. That’s the way of addiction, though. Come November, Republicans may discover that it’s too late to give up on whiteness. Because this time, it won’t just cost them an election. It may finally kill the party.