WATCH: Joe Biden says he’ll ‘develop some disease and resign’ if he and Kamala Harris disagree

In an interview with CNN's Jake Tapper, Biden recalled how he told former President Barack Obama that should the two encounter "fundamental disagreement" on a major "moral principle," he'd roll over and "develop some disease." He then described his potential dealings with Harris and their relationship behind-the-scenes.

"We are simpatico on our philosophy of government and simpatico on how we want to approach these issues that we are facing," Biden said. "When we disagree— so far, it's been just like when Barack and I did. It's in private. She'll say, 'I think we should do A, B, C, or D.' And I'll say, 'I like A, don't like B and C. And let's go, OK.'"

Biden continued: "And like I told Barack, if I reached something where there's a fundamental disagreement we have based on a moral principle, I'll develop some disease and say I have to resign."

Then Biden praised his current running mate's record as a California senator, specifically mentioning her work on the Senate Intelligence Committee.

Before becoming Biden's vice presidential pick, Harris vehemently expressed where she and the former vice president disagreed on the social justice front.

In June 2019, Harris torched Biden over his civil rights record and his friendship with two pro-segregation Democratic senators.

"I do not believe you are a racist," Harris slapped the backhanded epithet while on the Democratic primary debate stage. "I agree with you when you commit yourself to the importance of finding common ground."

But then she charged that his comments at a recent fundraiser—where he reflected on the days of "civility" in the Senate when he worked with two Democratic senators who supported segregation—were "personal" and "hurtful."

Harris alleged that those two senators "built their reputations and careers on segregation of race in this country."

As a "little girl in California who was part of the second class to integrate public schools" and "bused to school everyday," she noted that Biden also worked with those senators to "oppose busing."

During her presidential run, Harris additionally stated that she believed several of the women who accused Biden of unwanted touching.

"I believe them, and I respect them being able to tell their story and having the courage to do it," she said on the campaign trail in Nevada.

Then after the Democratic ticket was formalized, both candidates memory-holed what bad blood remained.