The former vice president has pointed to Saturday‘s South Carolina primary as crucial for his campaign. He told CBS' "Face the Nation" in an interview airing Sunday that he remains confident he will win the state.

Clyburn on Sunday said Tuesday’s debate in South Carolina — four days before the state votes — will be crucial for Biden, adding that he thought the large size of previous debates "unnerved" the former vice president.

"I think that at that time you had, what, 17 or 18 people on the stage. [California Sen.] Kamala Harris, I think, unnerved him a little bit with her question," Clyburn said. "So all of this changes when you only have six people. The dynamics on Tuesday night will be totally different from what they were."

But the South Carolina Democrat also said Sunday that if the primary vote were Monday in South Carolina, Biden would earn a lot of the African American vote.

"I don't know if I've spent enough time trying to figure out exactly who has how much, but all these candidates will get some African American votes. No question about that," he said.

"I do believe, however, that if we were having the election tomorrow, that Joe Biden would have more of the vote. How much more? I don't know yet," he added. "I think the debate on Tuesday night will have an impact."

Clyburn said he plans to endorse a candidate Wednesday.

"I just believe it would be, it would not be good for me to hold myself out as a person who has been in South Carolina politics for as long as I’ve been," he said.