Joe Biden’s choice of Kamala Harris as his running mate is one of the most fateful decisions of his political career. With Biden currently enjoying a healthy lead in the polls, there’s good reason to expect that Harris will make history in November by becoming the first female vice president, the first African American vice president, and the first Asian American vice president.

Nor is there any reason to think Harris’s career will end with the vice presidency. Given Biden’s age and his suggestion that he intends to serve only one term, the Democratic presidential nomination will likely be open in 2024, with Harris having a huge advantage over any potential rival. Since 1952, there have been five Democratic vice presidents: Lyndon Johnson, Hubert Humphrey, Walter Mondale, Al Gore, and Joe Biden. All five went on to become the presidential nominees of their party. Lyndon Johnson’s route to the nomination was through the assassination of John F. Kennedy. The rest leveraged their vice presidential status for a nomination. (To be sure, the value of having been vice president can deteriorate. After losing the general election in 1968, Humphrey lost his 1972 bid for the nomination.) But the lesson is clear: The path to the presidential nomination is through the vice presidency.

In picking Harris, Biden has likely set the course of his party for at least another decade. The choice of Harris makes sense given that she is much closer to Biden’s centrist politics than one of the other plausible candidates, Elizabeth Warren.

In fact, Harris is so logical a pick that it is worth asking why Biden seemed to be hesitant to make it. Over the last few months, there has been an unusual amount of closed-door drama in the Biden campaign, with many unlikely names (Susan Rice, Karen Bass) floated as alternatives. This suggests that Biden wasn’t wholly sure about whether to go with Harris.

Plausible reasons for Biden’s being gun-shy include resentment over Harris’s criticism of Biden during the primaries. Also, the rise of protests against the criminal justice system might have made Biden reluctant to pick someone with a record of being a tough prosecutor.

One other factor was repeatedly mentioned in press accounts. Some in Biden’s circle worried that Harris had too much “ambition.” This objection to Harris was rooted in pure sexism, the belief that assertive women are disruptive of the proper ordering of the world.

In fact, Harris’s ambitiousness is one of her virtues, and it’s something to be welcomed even by those who are wary of her centrist inclination. An ambitious politician is one who is likely to push a bolder agenda, with the hope of achieving a legacy.

Writing in The American Prospect, Harold Meyerson observed that Harris, “like Biden,” is “a political animal who understands that the nation, and the Democratic Party in particular, has moved left, and that the policies of a Biden administration, therefore, have to be more progressive than those of Clinton and Obama. How much more progressive, particularly as concerns the balance between capital and labor, we don’t really know.” Meyerson added that “she’s smart and malleable when pushed. And…progressives prevail only when they push malleable pols.”

This quality of malleability has been noted by observers across the political spectrum. John V. Last of the neoconservative website The Bulwark describes Harris similarly as “shrewd and politically malleable.” The radical magazine Jacobin writes, “Harris has shown the capacity to be moved leftwards when pressured by activism. This is no small thing.”

A joint statement made by two progressive groups, RootsAction.org and Progressive Democrats of America, makes the interesting case that Harris’s political flexibility could be both a problem and an opportunity for the left:

As we saw during her own presidential campaign, Kamala Harris is a political weather vane. First, she was for Medicare for All, then she wasn’t. She failed for years to hold police accountable for gross misconduct in California, then touted her commitment to police accountability in the wake of George Floyd’s murder. While her penchant for taking positions broadly palatable to the corporate donor class raises concerns about her dedication to progressive principles, her habit of aligning her stance with the prevailing political winds gives us some hope. We will fight every day to hold Vice President Harris to the higher ideals she often espouses, and make sure those winds blow decisively in the direction of a Green New Deal, Medicare for All, and a level playing field for working families everywhere.

Neither Joe Biden nor Kamala Harris has many strong ideological convictions. They have both amply demonstrated that they will bend in the direction of the wind. If the Biden/Harris team wins in November, then the most important political fact of the coming years will be which direction the wind is blowing. The unprecedented protest movement over police violence combined with the economic and health care crises are likely to inspire continued popular agitation. Perhaps the best hope that America has is that the ambition and flexibility of the Biden/Harris team will ensure that they will yield to the popular pressures they will almost certainly face.