Although Mr Biden has since formerly said he holds no “grudges” against his running mate for what she’s previously said against his campaign, her past remarks have still dominated the news cycle.
The Independent has rounded up the four key moments Mr Biden and Ms Harris have clashed ahead of being named on the same presidential ticket.
1. Mandatory school busing
Kamala Harris went out swinging against Joe Biden during the first Democratic presidential debate.
The California senator saw her chance to fluster the former vice president, who was leading among all Democratic candidates, and she found Mr Biden’s weakness: his past Senate record on mandatory busing in the 1970s.
“There was a little girl in California who was part of the second class to integrate her public schools, and she was bused to school every day. And that little girl was me,” Ms Harris said during the debate while targeting Mr Biden for opposing mandatory busing.
Mr Biden hit back by saying that was a “mischaracterisation” of his position in the Senate, but it went down as the most contentious moment between the politicians during the presidential campaign.
The comments thrust segregationist policies onto a national stage, and Ms Harris again repeated her criticisms against the former vice president at the following debate.
“Had I been in the United States Senate at that time, I would’ve been completely on the other side of the aisle, and let’s be clear about this: had those segregationists their way, I would not be a member of the United States Senate,” she said. “So on that issue, we could not be more apart.”
2. Sexual assault allegations against Mr Biden
In April 2019, prior to Mr Biden entering the presidential race, reports surfaced of the former vice president inappropriately touching women.
When asked by reporters, Ms Harris said she believed the women who spoke out against her now-running mate.
“I believe them, and I respect them being able to tell their story and having the courage to do it,” she said.
Multiple women accused Mr Biden of inappropriately touching them, including one Nevada politician who said the former vice president came up to her at a 2014 campaign stop and kissed the back of her head. This encouraged Mr Biden to release a video addressing the allegations against him.
“Social norms are changing. I understand that, and I’ve heard what these women are saying. Politics to me has always been about making connections, but I will be more mindful about respecting personal space in the future. That’s my responsibility and I will meet it,” he said.
Then Tara Reade, a former aide to Mr Biden, came forward about allegations of sexual assault when he was a US senator, all of which he has vehemently denied.
Ms Harris, who was a potential vice president candidate at the time, was asked about the allegations, saying Ms Reade “has a right to tell her story”.
“And I believe that and I believe Joe Biden believes that, too,” she said on the San Francisco Chronicle podcast.
3. Medicare for All
Another prominent debate moment between Ms Harris and Mr Biden happened when discussing the American healthcare system.
This was a point of contention among many of the Democratic candidates at the time, with voters able to draw a distinct line between those who were for a plan like Medicare for All, which Ms Harris supported, versus those like Mr Biden who wanted to expand on the Affordable Care Act.
After listening to voters, Ms Harris devised her own Medicare-for-All plan that would take 10 years to implement and involved slowly transitioning every American over into a single-payer system.
“I listened to the American families who said four years is just not enough to transition into this new plan, so I devised a plan where it’s going to be 10 years of a transition. I listened to American families who said ‘I want an option that will be under your Medicare system that allows a private plan,”’ the California senator said during a debate after changing her plan multiple times throughout her campaign.
Mr Biden, who has been a proponent of keeping private health insurance for those who want it while expanding on the Affordable Care Act, disagreed at the time.
“Well, my response is that the senator has had several plans so far. And any time someone tells you you’re going to get something good in 10 years, you should wonder why it takes 10 years,” he said.
“If you noticed, there is no talk about the fact that the plan in 10 years will cost $3 trillion. You will lose your employer-based insurance. And in fact, you know, this is the single most important issue facing the public.”
4. Bringing more police to the streets
In 2002, then-Senator Joe Biden penned an op-ed for the Delaware State News that reacted to the rising national crime rate, which was happening for the first time in 10 years. What was his solution to the rise in crime? More police on the streets.
“What works in the fight against crime? It’s simple – more police on the streets,” he wrote. “Put a cop on three of four corners and guess where the crime is going to be committed? On the fourth corner, where the cop isn’t. More cops clearly means less crime.”
This was during the “tough on crime” era of the Democratic party in the 1990s and early 2000s.
Now Mr Biden stands as a presidential candidate of a major political party during a time in the country where there is a nationwide call for police reform. Although his views have likely altered since that op-ed, Mr Biden did state he was not for the “defund the police” movement taking over on the far left of his party.
But his running mate has said she would be for “reimagining” police in the US.
“I think that a big part of this conversation really is about reimagining how we do public safety in America which I support which is this: we have confused the idea that to achieve safety, you put more cops on the street instead of understanding to achieve safe and healthy communities,” Ms Harris said.
“That’s how I think about this,” she added. “You know, in many cities in America, over one-third of their city budget goes to the police. So, we have to have this conversation, what are we doing? What about the money going to social services? What about the money going to helping people with job training? What about the mental health issues that communities are being plagued with for which we’re putting no resources?”
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