Democratic presidential nominee Joe Biden is an intensely risk-averse politician. In his nearly 50 years in public life, he has always positioned himself in the middle of the Democratic Party — not too far right or too far left. He spent roughly a decade and a half in the Senate, making connections and deepening his understanding of politics, before trying to run for president for the first time. And in the 2020 primary, he refused to advocate for Medicare-for-all, support reparations for slavery or take other stances that could damage him in the general election.

In his vice-presidential search, Biden again took the safe route. Sen. Kamala D. Harris (D-Calif.) — his newly announced running mate — is a historic choice as a Black and Asian American woman, but she’s also a small-c conservative pick. Harris isn’t apt to cause any problems for Biden on the campaign trail, and her presence on the ticket will preemptively smooth over demographic concerns, bringing both relative youth and diversity important to a party increasingly reliant on people of color. Harris might not add many voters to the campaign, but she’ll help Biden run out the clock — and that’s exactly what he needs to do.

Right now, Biden is running the campaign equivalent of a “prevent defense” strategy in football. He’s not dominating the news cycle, and he doesn’t need to — every day that President Trump wastes on a bizarre tweet or a bad news conference is one that Biden wins. Harris is a good pick because she won’t disrupt that pattern. The national media already knows who she is and vetted her during the 2020 presidential primary. She has shown that she’s a talented speaker, and she’ll likely perform well on the campaign trail and in her debate with Vice President Pence.

She’s not the most moderate pick available to Biden, but the inevitable “socialist” attack line won’t work quite as well as it would with someone like Sen. Elizabeth Warren (D-Mass.). Trump tried this approach after the announcement Tuesday, labeling Harris “just about the most liberal person in the U.S. Senate,” and observing, “I would have thought that Biden would have tried to stay away from that a little bit.” But it’s going to be hard to make that stick. Harris is far less liberal than Warren or Sen. Bernie Sanders (I-Vt.).

In short, there’s no reason to think Harris would spoil Biden’s eight-point lead over Trump — and that’s a big point in her favor.

Harris also helps Biden preemptively solve some of his demographic problems.

Biden is 77, and if he wins the election he’ll be the oldest president to take office. If he had picked a running mate also in her 70s, as is Warren, he would have spent much of the campaign — and his early days in office — fending off questions about the collective ticket’s age and any health problems they might develop. But Harris is squarely in her 50s, which is, according to the plurality of Democrats, the ideal age for a president. She’s in a sweet spot where she’s old enough to have sufficient experience and young enough to allay health concerns.

Just as importantly, Harris brings racial diversity. Democrats want to be the party of racial equality: Ever since Michael Brown was shot in Ferguson, Mo., in 2014, Democratic voters have been moving left on race and are more willing than ever to attribute racial inequities to systemic discrimination. This summer, Democrats largely embraced the nationwide protests against racism and police brutality. By picking Harris, Biden has acknowledged the importance of those movements, and of his own reliance on Black voters. If he had picked a different candidate, he might have alienated his allies and stirred up dissension only weeks before early voting begins.

At the same time, there’s no clear regional or swing-state advantage from picking Harris. Democrats already have California firmly in the bag. Harris doesn’t help Biden bring back a wayward element of the party: The vast majority of voters passed on her during the primary, and Biden seems to have already unified the backers of his former opponents.

But Harris doesn’t need to add voters to the Democratic coalition. Biden already has enough support to win. He just needed to find a partner who could help him hold onto that lead and govern well if he wins.

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