Republican leaders are in a fix. Donald Trump, the GOP’s presumptive nominee, has made so many controversial statements that party leaders worry about his impact in November. His candidacy may hurt Republicans running for state and local office. Some Republican leaders in Washington wish their party could reject Trump and choose a different standard bearer. But they are afraid to speak up. They don’t want to alienate Trump’s supporters or incur Trump’s wrath.

How did the Grand Old Party get into in this mess? Why has the party that fielded broadly popular and accomplished political figures for national leadership such as Dwight D. Eisenhower, Ronald Reagan, and George H.W. Bush settled on a candidate like Trump with a 70% unfavorability rating (according to a Washington Post/ABC News poll released on June 15)? Why is the Party ready to nominate a candidate devoid of experience in public office? Pundits will be mulling over these questions throughout the campaign.

When searching for answers, they may find it useful to consider the historical situation that made Trump’s ascendancy possible. This is not the first time that an individual lacking in presidential timber became a Republican contender. Since 1988, several GOP candidates for president and vice president lacked impressive qualifications for national leadership.

Candidates’ shortcomings became notably evident in nominations for Vice President. In 1988 George H. W. Bush chose as his running mate Indiana senator Dan Quayle. Party strategists recommended Quayle, believing his youth and good looks could help the ticket. But Dan Quayle’s statements soon raised doubts. Quayle said, “I loveCalifornia. I practically grew up in Phoenix.” On another occasion he announced, “I have made good judgments in the past. I have made good judgments in the future.” During a televised debate, a moderator repeatedly asked Quayle what he would first do if the president died or became incapacitated. Quayle stumbled, seeming unable to identify how he would deal with such an emergency.

Twenty years later the Party’s choice for vice president set off greater alarm. During the 2008 presidential campaign, GOP presidential candidate John McCain’s selected Alaska governor Sarah Palin as his running mate. Conservative pundits had been recommending her for the vice presidency, especially William Kristol, who met her during a visit to Alaska. With just days before the national convention, John McCain realized that his preferred choice, Joe Lieberman, was unacceptable to social conservatives. After a frantic search that relied heavily on the Internet, advisers focused on Palin. She could help the campaign, strategists believed, because she was a woman, strikingly beautiful, and had the reputation of a maverick – an image McCain wanted to convey. With very little vetting, McCain named her. Republican leaders later discovered that Sarah Palin was poorly informed about national and international affairs and grossly unprepared for top leadership.

Democrats are not consistent exemplars of talent selection, of course, but in recent decades they have produced stronger candidates for vice president. Since 1988, the Democrats’ choices included U.S. senators with considerable political experience: Lloyd Bentsen, Al Gore, Joe Lieberman, and Joe Biden. Only one selection since 1988 now appears seriously flawed: the choice of John Edwards, the Democrats’ nominee for vice president in 2004. But scandals that wrecked Edwards’s political career came to light years after the 2004 presidential election.

Since 1988, candidates in the GOP’s presidential races have also raised questions about readiness for national leadership. In 2000 party leaders advanced the candidacy of George W. Bush, even though the Texas governor lacked a strong grasp of national and international issues. When Bush became president and dealt with the 9/11 tragedy, Iraq, Hurricane Katrina and other challenges, his shortcomings were abundantly evident. Sometimes Vice President, Dick Cheney appeared to have greater influence over decision-making at the White House.

During the 2012 primary contests, several weak candidates in the Republican field received enthusiastic backing from wealthy supporters and grassroots partisans. They briefly rose in popularity and then slipped. Texas Governor Rick Perry attracted interest (and money) but stumbled after speaking on-camera. Congresswoman Michele Bachmann, businessman Herman Cain, and former Congressman Newt Gingrich looked like major contenders for a short time but quickly lost favor after receiving scrutiny in the news media. Other candidates appealed to specific constituencies. Rick Santorum, for instance, received support from evangelicals but failed to attract broader support.

A related pattern appeared during the 2016 primaries. Candidates that lacked experience in government enjoyed brief moments of popularity. Dr. Ben Carson’s fortunes surged. He burned out after his lack of political knowledge became evident. Carly Fiorina, a tough-talking former CEO at Hewlett Packard, also drew interest. She, too, quickly wilted. And, of course, many Republican voters favored Donald Trump, despite his frequent plunges into controversy.

Republican leaders should have recognized that a crisis like the current one was a likely outcome after the party established a low bar for presidential and vice presidential aspirants. When a political party denounces government repeatedly and characterizes entrepreneurs as heroes while denigrating “bureaucrats” in Washington, partisans believe anyone can handle the president’s job, even a real estate mogul and reality game show host. When a party allows conservative radicals to impose restrictive tests of ideological purity on presidential hopefuls, talented individuals who are experienced in negotiation and compromise recognize that they cannot compete in the primaries (or, like Jon Huntsman in 2012 and John Kasich in 2016, they do compete but fail to attract much voter support). When a party allows strident commentators on radio, television, and the Internet to wield extraordinary influence in its affairs, a candidate who skillfully employs their techniques can emerge as the presumptive nominee.

Reporting on the Republicans’ race for the White House has concentrated too heavily on the bombast of Donald Trump. That emphasis suggests Trump is revolutionizing GOP politics through the force of his personality. A broader view of Republican practices since 1988 suggests that Donald Trump has not single-handedly shaped his opportunities. In recent years the Republican Party has provided a megaphone for numerous candidates that lacked experience, skills and broad appeal. That tolerance for resume-challenged candidates helped to clear a path for Donald Trump’s march to the Republican national convention.