In a career of unprincipled partisanship and playing it both ways, Saturday marked a new high for Senate Minority Leader Mitch McConnell (R-Ky.). But it also showed a leader in peril and the work he has to do to shore up the Republican Party.

On Saturday, McConnell and 42 other Republicans voted to acquit former president Donald Trump for the crime of leading an insurrection. But immediately after voting to acquit, McConnell gave a blistering speech mincing no words. “Former President Trump’s actions that preceded the riot were a disgraceful, disgraceful dereliction of duty,” McConnell said. “Trump is practically and morally responsible for provoking the events” of Jan. 6.

McConnell’s effort to have it both ways demonstrates the trouble he faces in deciding what to do with Trump supporters — a challenge he seemed to acknowledge in a post-impeachment interview with Politico. On the one hand, he has condemned what he called the “loony lies and conspiracy theories” of the likes of Rep. Marjorie Taylor Greene (R-Ga.) and promised to aggressively involve himself in primary elections in 2022. He views purveyors of paranoia like Greene as “a cancer for the Republican Party and our country.” On the other hand, however, many think he voted to acquit a man he knew was guilty because he was afraid of alienating the farther reaches of his party. (McConnell cited constitutional arguments about post-presidency impeachments.)

In dancing this dance, McConnell might well look to the Republican Party a half-century ago as a guide. Before the GOP’s ascendancy into the powerful party of Ronald Reagan, right-wing leaders of the 1950s and 1960s had to cut out the extremists among them to make conservatism acceptable to broad swaths of Americans. Only after they had done so were they able to take over the Republican Party and shift the center of political gravity in the United States to the right.

In the 1950s and 1960s, William F. Buckley Jr. led the charge against fringe elements on the right. Steeped in conservative thought as a child, Buckley learned from his father to oppose the New Deal, hate communism and preserve what he saw as the Christian heritage of the country. As Buckley came of age, he wanted to become a “salesman” for conservatism, as he put it.

The problem? Right-wing thought was too far beyond the pale of acceptability for prime time. Its outer reaches needed trimming. So that is exactly what Buckley did. Through National Review, the magazine he founded in 1955 and edited for more than 50 years, and “Firing Line,” the television show he launched in 1966 and hosted for more than 30 years, Buckley sought to make conservatism safe for America.

First, Buckley went after the antisemites. Before he rose to prominence, the American right in the 1920s and 1930s was virulently antisemitic, blaming the Great Depression on a Jewish conspiracy to take power, redefining the New Deal as a Jewish attempt to spread wealth in the direction of communism (relabeling the New Deal the “Jew Deal”) and calling Franklin D. Roosevelt a “Jew lover” doing the bidding of Jewish bankers. The Rev. Father Charles Coughlin was perhaps the most virulent of the right-wing leaders in besmirching Jews and accusing them of debasing a pure Christian civilization built throughout the Western world. He went so far as to suggest in 1938, “When we get through with the Jews in America, they’ll think the treatment they received in Germany was nothing.”

Buckley’s father was of this stripe. But Buckley was not convinced. In the 1940s, one of his closest college friends was Jewish. Plus, as a veteran, Buckley had imbibed the tolerant spirit of World War II, when the United States defined itself in opposition to Adolf Hitler.

So Buckley disavowed his father’s antisemitism, and then he removed its claws from the right. First, he did so quietly, dismissing the virulent letters he got from antisemitic thinkers who assumed he would be sympathetic to their screeds.

In the late 1950s, he became more aggressive. In the opening statement of National Review, Buckley warned against the “irresponsible right.” He later stated that “conservatism must be wiped clean of the parasitic cant that defaces it.” When in 1959 another conservative magazine, the American Mercury, grew increasingly antisemitic, including endorsing the fraudulent but potent “Protocols of the Elders of Zion,” which supposedly revealed a Jewish conspiracy to take over the world, Buckley took a stronger stand. He crafted a memo to conservative writers saying that National Review, the growing star of the right, would not publish the work of anyone whose name appeared on the masthead of the American Mercury.

It worked. After Buckley’s announcement, several other right-wing commentators and politicians disavowed the American Mercury, suggesting that the right was no longer willing to condone open antisemites. The right, to be respectable in America, could no longer openly showcase hatred of Jews.

There was more to cull. Buckley was worried, too, that right-wingers in America were tempted to become too individualistic. Here, his target was Ayn Rand, the author of such teenage cult classics as “The Fountainhead” and “Atlas Shrugged.” In her books, Rand developed her philosophy of “objectivism” as a forerunner to the “greed is good” culture epitomized by Gordon Gekko in the 1980s. The closing scene of Rand’s 1957 book “Atlas Shrugged” has its hero overlooking a destroyed civilization before, in a moment of rebirth, scrawling into the ground a dollar sign.

Buckley hated this crass materialism. As a salesman for the right, he realized that Rand epitomized everything the left mocked the right for being — greedy, selfish, unprincipled except in the name of hubris. Buckley immediately had Whittaker Chambers — a former communist spy who recanted, named names and became a famous conservative thinker — write a scathing review of “Atlas Shrugged” in National Review. Chambers called the novel “Big Sister Is Watching You,” and he took no prisoners, dismissing it as “a remarkably silly book,” so bad “that any ordinarily sensible head could not possibly take it seriously.”

Rand never spoke to Buckley again. She even refused to enter a room in which he was present. Buckley did not care. He applauded the effort to “read Miss Rand right out of the conservative movement,” suggesting that this was “in part the result of her desiccated philosophy’s conclusive incompatibility with the conservative’s emphasis on transcendence, intellectual and moral.”

By the early 1960s, Rand was little more than a cult favorite from the 1950s.

Into the 1960s, Buckley continued to police the right. When a group of anticommunists called the John Birch Society grew to prominence on the theory that President Dwight D. Eisenhower was a closeted communist leading a socialist revolution in America, Buckley condemned them, saying, “There are bounds to the dictum, Anyone on the right is my ally.” The Birchers and their unfounded conspiracy theories would emerge again and again, but Buckley insisted on keeping them out of the movement. He knew that if conservatives embraced the “drivel” of the John Birch Society, they would lose “20 to 30 million” Americans who, although generally conservative, “will pass by crackpot alley, and will not pause until they fell the warm embrace of those way over on the other side, the Liberals.”

By the mid-1960s, virulent antisemites, followers of Rand and the John Birch Society had become increasingly marginal to the conservative movement. Buckley, meanwhile, was helping Barry Goldwater win the Republican nomination for the presidency, and doing so with a message that conservatives were not hate-filled cranks out to do little more than enrich themselves. He and Goldwater argued that they were responsible, fiscally conservative adults who did not want to embrace social change too quickly.

Buckley, who in 1991 would receive the Presidential Medal of Freedom from George H.W. Bush, continued to hold sway within the American right for the remainder of the 20th century, mainly by making conservatism safe for America.

This is what McConnell is tasked with. His challenge is keeping the cranks at bay. The problem is that they have been creeping in for a while now.

The “greed is good” sentiment came back into right-wing politics first. Alan Greenspan was a disciple of Rand (he called “Atlas Shrugged” a “magnificent masterpiece”), although he made peace with the welfare state and the necessity of the government before he became President Gerald Ford’s chief economic adviser and chair of the Federal Reserve. Paul D. Ryan, the former speaker of the House, also famously made all his congressional interns read the novel. (It should be noted that Ryan first read Rand in high school and never grew out of it.)

Now, with Trump, we are beginning to see antisemitism creep its way back into prominent right-wing expression. Seeing offensive antisemitic T-shirts at the Jan. 6 Capitol riot suggests that today’s right is allowing crass, bigoted expression to reenter its midst.

If McConnell wants the right wing to remain a prominent force in American politics, he should look to Buckley. As much as this conservative trailblazer loved “triggering the libs” in his own time, he recognized the necessity of shaving off the most egregious members of his congregation.