The election of Kamala Harris would be a first. Since 1836, only an incumbent vice president has been elected president.

NEW YORK (AP) — As Vice President Kamala Harris she begins Autumn campaign As for the White House, she can look back on history and hope for better luck than others in her position who have tried the same thing.

Since 1836 there has been only one serving vice president, George HW Bush in 1988was elected to the White House. Those who tried and failed included Richard Nixon in 1960, Hubert Humphrey in 1968, and Al Gore in 2000. All three lost in close elections that were dominated by issues ranging from war and scandal to crime and the intricacies of televised debates. But for each vice president, two other factors proved decisive: whether the incumbent president was popular and whether the president and vice president had a productive relationship.

“You really want those elements to come together,” says Julian Zelizer, a professor of history and public affairs at Princeton University. “If the person the vice president is working for is popular, that means people like what he's doing, and you can capitalize on that. And you need to make sure the two main people are working together.”

In 1988, Bush easily defeated Democrat Michael Dukakis, the governor of Massachusetts, whom Republicans dismissed as incompetent and out of touch with the world. Otherwise, Bush benefited from a solid economy, the easing of the Cold War, and a rare streak of good fortune for a vice president. President Ronald Reagan's approval ratings rose during the year after a sharp drop in the wake of the Iran-Contra scandal in 1986-87, and Reagan and Bush worked well together on the campaign trail. Reagan openly supported his vice president, who ran against him in the 1980 primaries. He praised Bush as a dedicated and invaluable partner at the Republican National Convention, appeared with him at a rally in California, and spoke at rallies in Michigan, New Jersey, and Missouri.

“Reagan was not a man who held grudges,” said historian and journalist Jonathan Darman. “And Bush navigated the complexities of their relationship well during his tenure as vice president.”

Former Vice Presidents who ran

When Gore ran for office in 2000, he had advantages similar to those of George HW Bush. The economy was strong, the country was at peace, and President Bill Clinton enjoyed high approval ratings despite his impeachment over his affair with White House intern Monica Lewinsky.

Gore had worked closely with Clinton over the previous eight years, but the scandal led to ongoing tensions between them. He downplayed the president's presence during the campaign and referred to himself as “my own man” in his acceptance speech at the Democratic National Convention. Commentators described his distance from Clinton as a setback in a historically close racewhich was decided in Florida by a majority of less than 1,000 votes.

“Instead of finding a way to recognize the accomplishments of the Clinton administration, Gore ran from Clinton as fast as his legs would carry him,” wrote Jacob Weisberg of Slate shortly after the election.

Like Gore, Nixon was unable or unwilling to capitalize on the popularity of incumbent President Dwight Eisenhower. In 1960, as his second term neared its end, Eisenhower was still so popular that Nixon's opponent, Democrat John F. Kennedy, feared that the president's active support might prove decisive. But Eisenhower's relationship with Nixon was complicated, and had been since Eisenhower's candidacy eight years earlier. He had chosen Nixon as his running mate but nearly dropped him over the so-called Checkers scandal, in which Nixon was accused of misusing funds from political supporters.

Nixon was more than 20 years younger than Eisenhower, the victorious World War II commander who often viewed his vice president as a junior officer, according to Nixon's biographer John A. Farrell. At the end of a summer 1960 press conference, Eisenhower was asked to name Nixon's influence on a major decision. He replied, “If you give me a week, I might think of one.” Meanwhile, Nixon was reluctant to campaign for Eisenhower, out of a desire to go his own way and reportedly also out of concern for the 70-year-old president.

“Nixon was determined to be his own man,” says Farrell, whose award-winning book “Richard Nixon” was published in 2017. “He always said he was concerned about Eisenhower's health, but there are also anecdotes that Eisenhower was upset about it. Both could be true.”

Nixon's luck changed when he ran against Lyndon B. Johnson's vice president eight years later. No vice president had been more entrapped by his predecessor than Hubert Humphrey, whose candidacy was only possible because Johnson decided not to seek re-election.

Humphrey faced challenges within the party from anti-war candidates Eugene McCarthy and Robert F. Kennedy (who was assassinated in June 1968 after winning the California primary) and was aligned with Johnson's divisive, warmongering stance.

Humphrey privately advocated a less harsh approach to the war, but was intimidated and silenced by Johnson, and in many polls he was well behind Nixon. It was not until the fall that Humphrey deviated from this line and called for a halt to the bombing of North Vietnam. The vice president recovered, but lost the popular vote by less than one percentage point and failed even more clearly in the electoral college.

“Johnson, in my opinion, did catastrophic damage to Humphrey,” says Michael Cohen, a Boston Globe columnist and author of a book about the 1968 election called “American Carnage.”

How is Harris?

Like Johnson, President Joe Biden he explained would not seek a new term less than a year before Election Day, although he waited much longer in the election cycle than Johnson. Unlike Humphrey, Harris quickly consolidated Democratic support and accepted her party's nomination in a uplifting convention the castle without significant damage from protestsunlike the violent event of 1968 in the same city, Chicago.

In an AP-NORC poll conducted in July after Biden dropped out of the race, about 4 in 10 Americans were satisfied with his performance as president, roughly in line with his approval ratings since the summer of 2021 and comparable to those of the Republican candidate. Donald TrumpEisenhower, Reagan and Clinton often had higher approval ratings than Biden, even though they all served in less polarized eras.

Harris wants to succeed a president who was himself vice president and ran for president four years later. Barack Obama Biden from running for election in 2016 and was waiting to support Biden in 2020 until the crowded field of the Democratic primaries was clear.

“Obama became an enthusiastic supporter, which helped unify the party at a time when Biden's behavior on race in the 1990s, including his support for the crime bill, raised doubts among young progressive voters,” says Biden biographer Evan Osnos. “Obama's support for Biden was more than his candidacy; it was about his character, and that proved to be important.”

As president, Biden has sought to include Harris in his major policy decisions and conversations with foreign leaders. He has promised to be Harris's top campaign aide and to do whatever she asks of him to get her elected, though his aides are still mulling over where best to deploy the still-unpopular president. On Labor Day, Biden and Harris will appear together in Pittsburgh at a campaign rally in a key swing state, Pennsylvania.

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Amelia Thomson-DeVeaux, polling editor for the Associated Press in Washington, contributed to this report.