FOX NEWS -- New book goes behind the scenes and reveals the dirt behind the chaotic 2024 election

Reporter and author Jonathan Allen said Tuesday that former President Barack Obama was working against Vice President Kamala Harris after President Joe Biden dropped out, advocating for an open primary because he didn't think Harris could win.

"President Obama absolutely did not think that Joe Biden should continue, according to our sources close to President Obama," Allen told MSNBC. "And he also didn’t want Kamala Harris to be the replacement for Biden. He didn’t think that she was the best choice for Democrats, and he worked really behind the scenes for a long time to try to have a mini-primary, or an open convention, or a mini-primary leading to an open convention, did not have faith in her ability to win the election."

Allen, a senior politics reporter at NBC News, and Amie Parnes, a senior political correspondent for The Hill, joined MSNBC to discuss their new book set to be released this month, titled, "FIGHT: Inside the Wildest Battle for the White House."

"As it turned out, she didn’t win, but he was really working against her," Allen continued.

Allen also said Obama was not willing to endorse Harris when he talked to the vice president on the day Biden dropped out.

Obama and former first lady Michelle Obama did eventually endorse Harris, but their support came five days after the president announced he was dropping out and endorsed Harris himself.

"In one moment, he had set up a phone call with Congressman [James] Clyburn from South Carolina on the day that Joe Biden handed off the baton to Kamala Harris, and Obama had set up a call with Clyburn for like 5:30 that afternoon. And Clyburn thought to himself, this guy is going to try to rope me into the open convention thing, I better get my endorsement of Harris out there fast, so this is a short conversation," Allen said. 

Obama and Harris' offices did not immediately return requests for comment.