Democratic presidential nominee Joe Biden has passed a key test of his strength as a presidential candidate. Biden’s choice of Kamala Harris as his running mate shows vision, thoroughness and poise — three qualities sorely lacking in the current officeholder.

Harris has a long record as a pragmatic leader and, as a West Coast political figure, brings welcome geographic diversity to the ticket. She can take office as a well-versed powerful advocate on many issues Washington shares with California — including water rights, wildfire control and public-lands management.

And as the daughter of immigrants with extensive governmental experience in a large, diverse state, she is well-versed in a broad range of urgent societal needs — such as policing reform. In two terms as California’s attorney general and in the U.S. Senate since 2017, she emerged as a leader for environmental justice and fighting climate change, both areas the next presidential administration must repair after catastrophic deregulation by the current one.

Drawing on her prosecutorial background, she became a rigorous, sometimes feared, questioner in Senate hearings. Her toughness in Democratic primary debates indicates she’ll hold Vice President Mike Pence directly accountable for the long list of failures of President Donald Trump’s disastrous term. Indeed, one of the questions she faced about whether she’d be a good running mate was whether she’d been too hard on Biden during debates. And she liked him. 

But presidential elections rarely swing on the qualifications of the vice presidential nominee. This is why Harris’ selection should be assessed for what it says about Biden’s judgment.

Shortly after emerging atop a crowded field of nomination-seekers, Biden committed to having a female running mate. Winning in 2020 requires bridging many divides. By reaching out for a formidable running mate of a different gender, generation, race and region, Biden shows how America’s diversity ought to be regarded: a unique national strength.  

Biden showed he can be a bridge, and that he has the poise to bring aboard a teammate who challenged him sharply in public debates. While Trump requires deference from all, Biden knows the value of a fearless opposing voice firsthand. His public break from President Barack Obama’s stated views on gay marriage proved an influential moment for advancing that civil right. 

That’s what he’s added with Kamala Harris, and he knows it. She’s extensively prepared to be a heartbeat away from the presidency, and more than able to be a strong partner throughout Biden’s service. Vote Biden-Harris.