Tuesday night, following the fourth Republican presidential primary debate, the pundit class will dutifully declare Marco Rubio the winner, extolling his debate prowess with the usual breathlessness. And then, the overnight polls will find that once again, Donald Trump has won the night (with Washington GOP bête noir Ted Cruz likely coming in second), and establishment GOP heads will explode again.

The Trump phenomenon might feel both interminable and unprecedented to Republican elites, but of course it isn’t. American populist politics has a long tradition, from Andrew Jackson to Huey Long to Joseph McCarthy. But the politician Trump is most like could be George Wallace. And if the rumors of an establishment plot to somehow prevent the current frontrunner from getting the nomination are true, Trump could wind up as the GOP’s Wallace in more than just style and bluster.

Back in Wallace’s day, it was Democrats, not Republicans, who were bedeviled by their extremist flank. The Southern wing of the party was in full rebellion over the push for racial integration in schools and public accommodations; over the civil rights laws pushed through by a majority Democratic congress with the help of Republicans and an apostate Southern Democratic president; and even over the war in Vietnam, which drew a spirited investigation by ardent segregationist Sen. William Fulbright of Arkansas.

Wallace ran for Alabama governor in 1958 touting his ability to “to treat a man fair, regardless of his color.” He lost and vowed to “never be out-niggered again.” He ran for governor in 1962, this time as a hard-line segregationist, and won. The new George Wallace was a political thespian, dramatically “tossing the gauntlet before the feet of tyranny” on behalf of the “great Anglo Saxon Southland” and declaring “segregation now and segregation forever.” He staged his “stand in” at the entrance of the University of Alabama in June of 1963 to dramatize the fruitless fight to keep two black students, and their armed federal escorts, out; and ran his soon-to-be ailing wife, Lurleen, for governor when the Democratic state legislature refused to let him vie for a second term.

In 1966, Wallace declared his independence from the political establishment, calling himself “an Alabama Democrat, not a national Democrat,” and adding: “I’m not kin to those folks. The difference between a national Democrat and an Alabama Democrat is like the difference between a Communist and a non-Communist." He commiserated with conservative white voters, saying both major parties have "looked down their nose at you and me a long time. They’ve called us rednecks—the Republicans and the Democrats. Well, we’re going to show there sure are a lot of rednecks in this country."

When he ran for president as an independent in 1968, Wallace did so as a pure populist, capitalizing on a segment of the electorate’s disdain for traditional politicians.

His campaign focused on law and order in the face of hundreds of riots in 1967. He declared it a “sad day in our country that you cannot walk even in your neighborhoods at night or even in the daytime because both national parties, in the last number of years, have kowtowed to every group of anarchists that have roamed the streets of San Francisco and Los Angeles and throughout the country.”

He zeroed in on white working-class voters’ anxieties over the decline of traditional values, deriding the Supreme Court for promoting a “perverted agenda" that ripped prayer from public schools while concocting a right to “distribute obscene pornography.” He lamented the inordinate amount of time Washington elites spent pandering to communistic black civil rights scoundrels and “welfare cheats” while prying into the affairs of the common white man who just wanted to run his business as he saw fit or sell his home to someone with “blue eyes and green skin” via restrictive covenant if he so chose.

Like Trump, Wallace rose steadily and improbably in the polls, with consistently high ratings for “saying it the way it really is” and “standing by his convictions.” New Republic columnist Richard Strout in 1967 dubbed Wallace “the ablest demagogue of our time, with a voice of venom and a gut knowledge of the prejudices of the low-income class.” Even John Wayne donated to his campaign, which raised most of its money through small donations.

By December 1967, Wallace made Gallup’s list of America’s 10 most admired men, at No. 8, one notch above California Gov. Ronald Reagan. Gallup would later note that Wallace’s support was strongest among those “with a high school background or less” and those who strongly disliked President Lyndon Johnson.

Wallace ran in some Democratic primaries, as he had briefly in 1964. But; his segregationist views had become an anathema to the party of LBJ, and he got almost no votes. Instead he accepted the nomination of the new, far-right American Independent Party, and he chose retired General Curtis LeMay, who wanted to nuke Vietnam, as his running mate.

Though his principal strength was in the South, Wallace also held large and raucous campaign rallies up North; drawing 20,000 people to Madison Square Garden in October 1968, as anti-Wallace protesters clashed with police outside. One Wallace strategist, arch-segregationist John J. Synon, boasted of Wallace’s Northern supporters in a 1967 column: “Who faced down M.L. King in Cicero, last summer [by throwing bottles and bricks at black civil rights activists who marched through the all-white Illinois town]; who takes the brunt whenever there is trouble? Blue collars, that’s who.”

Wallace’s campaign rallies were characterized by intermittent spasms of violence, including in New York, where several of his supporters notoriously surrounded a group of black protesters and began chanting “kill ’em! Kill ’em!” And Wallace, like Trump, seemed to encourage their bravado, declaring at Madison Square Garden: “We don’t have riots in Alabama. They start a riot down there, first one of ’em to pick up a brick gets a bullet in the brain, that’s all. And then you walk over to the next one and say, ‘All right, pick up a brick. We just want to see you pick up one of them bricks now.”

In the end, Wallace’s independent presidential run took more votes from Richard Nixon than from Hubert Humphrey—four out of five Wallace votes would have gone to Nixon were Wallace not in the race, pollsters concluded at the time, and Nixon won by fewer than 1 million votes, while Wallace pulled 9.9 million. Wallace won five states in the Deep South, along with more Electoral College votes, at 46, than any third-party candidate before or since (one “faithless elector” in North Carolina stubbornly cast a vote for Wallace over that state’s victor, Nixon). The results prompted Nixon campaign strategist Kevin Phillips in 1969 to devise the “Southern strategy” to capitalize on Wallace’s popularity with disaffected conservative white voters in the South.

By 1972, it was Nixon and the Republicans who would never be “out-niggered again.”

Wallace ran twice more for president, both times as a Democrat. He finished a close third to George McGovern and Humphrey in the 1972 primary and came in third again in 1976, behind Jerry Brown and Jimmy Carter. But he was returning to a party he had helped break, by accelerating the realignment of the two major parties that began in 1964. Wallace never came close to being president, but his 1968 bid helped kill the New Deal coalition of black and white working-class voters. The Democratic Party was forever changed.

Which brings us to the Republican Party in 2016.

If their George Wallace—Donald Trump—wins the nomination, the party’s die is cast with a message that’s doomed among the increasingly multiracial presidential-year electorate. If he loses but his opponents continue to pander, self-protectively, to the most hateful aspects of Trump’s message, that die is cast anyway.

If he loses, particularly through some convention gamesmanship, and his supporters decide he was robbed of the nomination by a party elite who looked down on him, and on them, Trump could launch a third-party effort of Wallace-like proportions and tear the GOP in two. And that, in the end, is what Republican elites fear most.