Senator Manchin, who has decided not to run for president after a few hours of speculation, is calling on the Democratic Party to hold a “mini-primary” to choose the nominee, instead of just anointing Vice President Harris. 

“The Democratic Party has gone too far left. The Republican Party has coalesced around Donald Trump on the far right. In the middle, where do you go?” Mr. Manchin said on CBS News. 

He said there should be a “vigorous … three-week primary process.”

Mr. Manchin says the vice president has not earned the nomination, and that it is wrong for her to simply be chosen so quickly. “No one else is willing to speak up. Everyone else is saying: ‘Well, we’re falling behind, guess we’re gonna get in line,’” Mr. Manchin said.

The senator admitted that he had been “pursuing” a possible presidential bid himself after President Biden got out of the race on Sunday, though ultimately it went nowhere. He called the former chairwoman of the Democratic National Committee, Donna Brazile, to inquire about how he might be able to run, and she informed him that he had to be a registered member of the party. 

“I am not going to be a candidate for president,” Mr. Manchin, who is now an independent, announced on Monday. During an interview with MSNBC, the senator said he wanted to see a governor take up the mantle, not Ms. Harris. He said he was partial to the governor of Pennsylvania, Josh Shapiro, the Kentucky governor, Andy Beshear, the North Carolina governor, Roy Cooper, Governor Whitmer, and the Illinois governor, J.B. Pritzker. 

Mr. Manchin did not commit to supporting Ms. Harris as the presidential candidate, saying he — like many Americans — wants to see more bipartisanship and moderation. “I wanna see what her platform is and her positions, I want to see where she lands on that,” Mr. Manchin said. When asked by CBS News’ Gayle King if Ms. Harris was “too far left,” Mr. Manchin said: “Absolutely. She knows that.”