Biden was 'torn' about picking VP Harris after presidential debate 'bull---': book

President Biden was "torn" about picking Vice President Harris as his running mate after describing her attack on him during a 2019 presidential debate as "f---ing bull---," according to a new book on insider Democratic politics.

Biden was split between Harris and Michigan Gov. Gretchen Whitmer, according to "Battle for the Soul: Inside the Democrats' Campaigns to Defeat Trump" by Edward-Isaac Dovere, which was released Tuesday. 

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Biden especially connected with Whitmer because they both had family members who died of the same kind of cancer. 

"Two days before Biden announced Harris, he called [House Majority Whip Jim] Clyburn," Dovere wrote. "A decision that he originally said would be made the first week in August had drifted already well into the second week. He knew, he knew, Biden told Clyburn, and though he was almost there, he was struggling. ‘I’m torn,’ he said, ‘between my head and my heart.’"

Biden and Harris already had history. He had been blindsided by her attack on him during a 2019 Democratic presidential primary debate.

During that debate, Harris criticized comments by the former vice president spotlighting his ability to find common ground during the 1970s with segregationist senators with whom he disagreed, and over his opposition decades ago to federally mandated school busing.

"Do you agree today that you were wrong to oppose busing in America?" Harris asked Biden during the debate.

"There was a little girl in California who was a part of the second class to integrate her public schools, and she was bused to school every day," she said. "And that little girl was me."

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Biden was "taken aback," Dovere wrote.

"She thought it was a fair hit," Dovere continued. "This is a debate, she said, and debates were supposed to be about differences. She wasn't running for VP, despite what so many people – Biden included – assumed. She was running to be president, to beat Biden and everyone else. She wanted everyone to know that. Onstage, she seized her moment."

"A few minutes later, the moderators paused for a commercial break," Dovere wrote. "Biden leaned over to Buttigieg, at the podium to his right. They barely knew each other, but Biden was looking for someone to share the moment with. ‘Well,’ he said. ‘That was some f---ing bull---.’"

Biden decided not to hold a grudge, but his wife Jill Biden reportedly did.

"With what he cares about, what he fights for, what he’s committed to, you get up there and call him a racist without basis?" Jill Biden reportedly said of Harris on a phone call with close supporters a week later. "Go f--- yourself." 

However, the first lady and Harris made headlines recently and appeared to have mended their relationship.

Biden's choice of Harris left other influential Democratic women, including Sen. Elizabeth Warren, D-Mass., behind. Biden would have picked Warren as his running mate if he had run in 2016, Dovere wrote. She lobbied hard to be the 2020 pick.

"Biden's vision had been to use the vetting process to elevate as many women as possible, boost their careers," Dovere wrote. "Because it dragged on so long, with political reporters stuck in lockdown with nothing else to do and no other story to chase, many of the women were left feeling the veepstakes were more like a pageant. ‘This is a horrible, horrible process,’ Warren said to Harris, when they ran into each other at the Capitol, where John Lewis laid in state a few weeks before Biden made the pick."

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Biden's team had misgivings about Harris, too, according to Dovere's book.

"Right as the process was peaking at the end of June, still- bitter Biden aides texted around to one another to mark the one- year anniversary of the hell Harris had brought down on them in the first debate," he wrote. "One sarcastically announced that morning on a phone call, ‘You know what today is? It’s the one year anniversary of "That Little Girl Was Me."’ The vetting committee leaned in hard during their interviews with her, remembering what a mess her presidential campaign had been. None of her presidential campaign aides would be allowed to join her staff, they told her. There would be no role for her family. They’d set the schedule. They’d set the parameters. All this was conveyed to her with an edge."

Fox News' Paul Steinhauser, Morgan Phillips and Andrew Murray contributed to this report.