You have to win first: What Joe Biden's pick of Kamala Harris tells us about Biden

The biggest impact of Joe Biden's choice of California Sen. Kamala Harris as his running mate?

It's likely to be what it tells voters about Biden.

Vice presidential candidates almost never affect the outcome of a presidential campaign one way or another. No running mate since Lyndon Johnson in 1960 is credited with pushing the ticket over the top, and not even controversial running mates like Sarah Palin in 2008 are blamed for costing the ticket a victory.

Harris' groundbreaking qualities may make more of a difference than usual by energizing African American and younger voters in a way Biden so far has struggled to do. She is both the first Black woman and the first Asian American person on a major party's ticket, and at age 55 she is a generation younger than her 77-year-old running mate.

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But more important, with this choice, Biden gave some signals about his view of the campaign, his approach toward decision-making, and the traits he would bring to governing if he wins.

First things first: You have to win before you can govern

For a groundbreaking choice, Harris was also a safe one. She has been elected statewide in California and undergone the vetting that is part of the presidential campaign. She has shown herself as a combative debater in the primaries and an effective questioner in Senate hearings.

Biden seemed drawn to the governing possibilities of former U.N. ambassador Susan Rice, but she had never run for elective office. California Rep. Karen Bass had controversies to explain over working in Cuba that had never come up when she was running for Congress in California. Atlanta Mayor Keisha Lance Bottom and Rep. Val Demings of Florida were fresh faces, but they had never run statewide, let alone in a national race.

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Biden has no interest in shaking up a race the polls show he's leading. Harris is more likely to follow the Hippocratic oath for running mates: Do no harm.

He won't be rushed on big decisions

Biden initially said he would announce his running mate on Aug. 1, then during the first week of August. Finally, a week after that, he unveiled his choice, with no apology for the delay.

That shouldn't have been a surprise. He blew past a series of self-declared deadlines to decide whether to run for president in 2016 (when he didn't) and in 2020 (when he did).

What's more, his campaign ran a tight ship. The choice didn't leak before the campaign was ready, sending it out in a blast text to supporters and others who had signed up. That discipline reflects in part the close counsel he keeps: His most trusted adviser is his wife, Jill. It's also consistent with the don't-rock-the-boat theory of the campaign, which has fared well even as Biden has been forced to spend most of his time at his home in Wilmington, Delaware, because of the coronavirus pandemic.

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He doesn't hold a grudge

Biden never looked more stunned during the primary campaign than when Harris questioned his record on race, demanding in one early debate, "Do you agree today that you were wrong to oppose busing in America?"

Biden angrily accused her of misrepresenting his position.

That may have been the high point of her campaign; it was one of the low points for him, and one that was especially unexpected by the Bidens because she had been a friend of Biden's son, Beau, when both were state attorneys general.

Biden's decision to tap her as running mate shows a willingness to move past a painful exchange that is sure to be replayed in opposition TV ads.

That contrast on that between Biden and President Trump – who seems to relish grievances – is hard to miss and likely to be more important than whatever Harris had said in that debate.

"It's very rare for people to actually vote for who they would rather see as vice president of the United States," said Christopher Devine, a political scientist at the University of Dayton whose book "Do Running Mates Matter?" was published this spring. "They matter mostly in how we evaluate the presidential candidates. The choice of a running mate says a lot about their priorities, about what kind of leadership skills that they want."

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In 1992, Democratic presidential candidate Bill Clinton's choice of Al Gore, a fellow baby boomer and a fellow Southerner, reinforced the idea that Clinton represented a new and more moderate Democratic Party.

The vice presidential candidate can also reassure voters about concerns they may have about the top of the ticket. The academic study by Devine and co-author Kyle Kopko found that voters who thought Biden was ready to become president, if necessary, became less concerned about whether presidential candidate Barack Obama had too little experience for the job.

Voters who thought Palin was ready to be president, if necessary, became less concerned about whether presidential candidate John McCain was too old for the job. That could be useful for Biden, too.

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This article originally appeared on USA TODAY: Joe Biden's choice of Kamala Harris tells voters about his traits