By Jon Keller

BOSTON (CBS) – Keep this in mind when assessing presumptive Democratic Presidential nominee Joe Biden’s choice of California Senator Kamala Harris as his running mate – it almost surely doesn’t matter.

The most common myth about VP picks is that they have geographical importance, diversifying the nominee’s regional appeal and boosting the ticket in the second-banana’s home state. This is unsupported by reality.

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But can’t a dud pick screw up a campaign? Not really.

There is no valid reason to think that George McGovern would have suffered a less-emphatic loss to Richard Nixon in 1972 had he not chosen Missouri Sen. Tom Eagleton, whose struggles with depression forced him off the ticket at a time when mental illness was more widely demonized than it is now.

The economic collapse of 2008 and Sen. John McCain’s inept response to it sealed his loss to Barack Obama, not Alaska Gov. Sarah Palin’s reading habits (or lack of them).

The Dukakis campaign thought Vice President George H.W. Bush’s selection of lightweight Indiana Sen. Dan Quayle in 1988 might sink his candidacy. It didn’t.

Still, when choosing a running mate, candidates are well-advised to follow the doctor’s doctrine – first, do no harm. And Biden has done no harm by choosing Harris.

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In an election where he needs a huge turnout by black and female voters, it won’t hurt to have a black female nominee. Any voters who would balk at that were surely not available to Biden anyway.

While Harris made a hash of her own presidential candidacy, she is an undeniably charismatic campaigner. Her assorted eviscerations of Trump-era figures unfortunate enough to appear in front of her committees made her a national figure, drew the ultimate back-handed presidential compliment (“nasty”), and raise the spectre of an unrelenting defenestration of Vice President Mike Pence in their October 7 debate. Oh, the Hoosieranity!

But perhaps most importantly, Harris gives the Biden campaign another shield to deflect one of the few offensive weapons remaining in the COVID-era Trump arsenal – his depiction of the Democrats as heathen leftists bent on unleashing violent crime.

As DA of San Francisco from 2004 to 2011, Harris boosted the felony conviction rate from 50% to 76%. Drug crime convictions also soared. She aggressively went after environmental crime, local political corruption and hate crimes, all while also innovating in reentry programs for nonviolent offenders that cut the recidivism rate and saved tax dollars.

During her six years as California’s attorney general, Harris promoted police accountability, consumer protection, and anti-truancy programs that to this day draw fire from the left. Good luck to the Republicans casting her as a let-‘em-loose lefty; they’ll need it.

And one final plus: by choosing to team up with a former competitor who leveled some of the presidential primary campaign’s most blistering attacks on him, Biden draws a clear distinction between himself and Trump that will likely help him secure the whopping women’s vote he will need to prevail: while the incumbent consistently lashes out with special venom at women who challenge him, Biden is modeling forgiveness and tolerance as he elevates his critic.

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And remember – the choice between Biden and Trump is what this election is all about.

Jon Keller