"...He described his relationship with his potential vice president in substantive terms, saying he has asked Harris to be the final sounding board before he makes decisions, much like the role he played for former President Obama.

“I asked Kamala to be the last one in the room. To always tell me the truth, which she will. To challenge my assumptions if she disagrees. Ask the hard questions,” he said. “That’s the way we make the best decisions for the American people....”

https://www.latimes.com/politics/story/2020-08-12/joe-biden-kamala-harris-wilmington