GOP leaders have unleashed a stunning level of vitriol against their party’s most successful presidential candidate.  House Speaker Paul Ryan (R-Wis.), emphatically declared last week that he was not ready to endorse Donald Trump, his party’s presumptive presidential nominee. This move was unprecedented in modern American history. Trump’s response was that Ryan may need to be replaced as head of the Republican National Convention.  Ryan’s rebuke reminds Americans that Trump is deeply unpopular, particularly among a significant number of powerful Republicans. Former GOP presidential nominee Mitt Romney belittled the GOP’s new leader as a moral cretin unfit to be the standard bearer. Former President George W. Bush and his father, President George H.W. Bush, both say they are not attending the GOP convention in Cleveland.  Such attacks, however, are nothing new.  Political elders have lambasted their party’s leading presidential contenders throughout U.S. history. The big difference now is that this battle is playing out in public. In the past, attacks were largely in party backrooms, behind closed doors.  To be sure, some serious breaks have been acted out in public. With dire results. President Theodore Roosevelt, for example, realized in 1912 that his progressive agenda was being abandoned by his chosen successor, William Howard Taft. TR challenged Taft in the Republican primaries. “We stand at Armageddon,” Roosevelt thundered at the convention, “and we battle for the Lord!”  When Taft prevailed, Roosevelt bolted the party. He ran as a third-party candidate in 1912 on a Progressive Party ticket. Ultimately, the Democratic nominee, Woodrow Wilson, won.  In most other cases, however, the internecine bloodletting took place in private, preserving the appearance of party unity and making it easier to heal any rifts.  The 1944 Republican nominee Thomas Dewey ignored former President Herbert Hoover at an important state funeral that October and drew the national leader’s ire. “Dewey has no inner reservoir of knowledge on which to draw for his thinking.” Hoover sneered to a friend. “A man couldn’t wear a mustache like that without having it affect his mind.”  Hoover, though, sought to keep his beliefs private  Former presidents have kept mum even when they see a nominee as a threat to their legacy. In 1964, for example, former President Dwight D. Eisenhower didn’t have much regard for Senator Barry Goldwater. The conservative firebrand had repudiated Eisenhower’s presidency as a “dime-store New Deal.” Nonetheless, Eisenhower gave only halting support to the party’s anti-Goldwater forces. Despite Eisenhower’s contempt, the Arizonan became the Republican nominee, only to lose in a landslide to President Lyndon B. Johnson.  Four years earlier, the Democratic power brokers were not as reticent. They viewed Senator John F. Kennedy, their party’s leading candidate in 1960, as too conservative and inexperienced. They disliked the campaign role of Joseph Kennedy, JFK’s father, and his controversial past. In addition, party leaders worried that JFK could not win national office because he was a Catholic.  During the primaries, Truman, the titular head of the party, told a TV news conference that a nominee should have “the greatest possible maturity and experience” -- a clear dig at JFK’s relative youth. The former president beseeched his party to hold a brokered convention and find a way to avoid nominating Kennedy. Eventually, however, Truman endorsed Kennedy in the general election, reasoning that GOP nominee Richard M. Nixon was worse  Adlai Stevenson, the Democratic nominee in 1952 and 1956, also refused to back Kennedy during the primary. Even Kennedy’s promise to name Stevenson as secretary of state could not persuade him.  Still, most of the party elders’ scathing criticism against JFK was confined to backroom conversations. Senate Majority Leader Lyndon B. Johnson, who also wanted the nomination, privately mocked Kennedy as “a scrawny little fellow with rickets.” Johnson urged Eisenhower to oppose Kennedy during the primary contest, calling him “a [Senate] nobody” and “a dangerous man.”  But Johnson’s efforts to stop Kennedy were not aired before the country in real time. In fact, 1960 demonstrated how the Democratic elders were able to prevent serious rifts from destroying their party’s chances. After securing the nomination, JFK offered — and LBJ accepted — the second slot on the ticket.  The resentment of party elders toward party nominees was often rooted in a sense that the candidate was repudiating a mentor’s record. In the 1960 GOP presidential race, for example, Eisenhower resented Vice President Nixon’s implication that he would offer more robust leadership. Close to Election Day, Ike was asked to name an instance when Nixon’s advice influenced a presidential decision. “If you give me a week,” Eisenhower replied, “I might think of one.”  In the reverse situation, Vice President Al Gore sought to distance himself from President Bill Clinton during the 2000 presidential campaign. Gore declared in his announcement that he would provide “moral leadership” and defend the American family — not-so-subtle knocks against Clinton’s sexual relationship with a White House intern, Monica Lewinsky. The bitterness between the two men festered and Gore never asked Clinton to campaign with him. After Gore lost to George W. Bush, Clinton upbraided his former vice president for running a lame, visionless campaign.  The current spectacle — in which former Senator Bob Dole will likely be the only past Republican presidential nominee to come to the convention and endorse the party’s standard bearer — is partly a function of Trump’s scorched-earth multi-media campaign. His attacks have been leveled personally, in real-time, via Twitter and cable news. Wounds are deeper, and could be harder to heal.  Trump’s presidential primary campaign is the apotheosis of the anti-Washington mood that has gripped presidential politics since Jimmy Carter’s 1976 White House run. One reason Trump vanquished his foes was because he ran against the GOP’s leadership as out-of-touch and inept.  This played out even as party elders have less power to shape national tickets — and outsiders more ability to tear down anything that smacks of Washington politics-as-usual.  Republican-on-Republican hits on Trump and his main rival, Ted Cruz, have contributed to the fraying of the GOP. The anti-Trump former presidents, as well as current and former party chairmen and congressional leaders, have much at stake. They are fighting for, as they see it, their legacies, their party’s future, their professional identities — and their own power.  In recent decades, party elders have been clinging to an increasingly tenuous position. Think former Majority Leader Eric Cantor, who lost a primary election, as Sarah Palin recently noted. Or former House Speaker John Boehner, who was unable to control his party’s Tea Party wing. Boehner is still so incensed that he called Senator Ted Cruz (R-Tex.) “Lucifer in the flesh.” As we are seeing now with Ryan, Trump’s ferocious public attacks could yet come back to haunt him. Unlike so many past presidential primaries, this rift might prove irreparable.  
Commentary: Party leaders often disliked their nominee. It’s the public vitriol that’s new.