Despite less-than-ideal finishes in the Democratic contests thus far, former Vice President Joe Biden said he's still confident he'll win the South Carolina primary with the help of African-American support.

"I feel good about where we are. I feel good about going into South Carolina. And I feel good about the kind of support I've had with African-Americans around the country," Biden told "Face the Nation" moderator Margaret Brennan in an interview to air Sunday.

WATCH: "I feel good about where we are. I feel good about going into South Carolina," @JoeBiden tells @margbrennan about his chances at winning the South Carolina primary. Tune in Sunday for more of Biden's interview only on @facethenation https://t.co/0vv55uyMzq pic.twitter.com/uHQktz4t1v — Face The Nation (@FaceTheNation) February 23, 2020

"So for South Carolina, what does this indicate to you? Because in the past, you were pretty confident you could pull off a win there," Brennan pressed.

"I still am," Biden replied. He expressed similar confidence in a positive result for the Nevada caucuses.

Biden maintained his spirit despite having faltered in the first two contests, coming in fourth in the Iowa caucuses and fifth in the New Hampshire primary. His campaign has argued the former vice president will do better in more diverse states, as both Iowa and New Hampshire are majority white.

Biden has focused particularly on South Carolina, where black voters are expected to make up 60% of the Democratic electorate in the coming primary. However, an NPR/PBS Newshour/Marist poll released Tuesday showed Biden's lead over Bernie Sanders among black voters has shrunk to just three percentage points.

A CBS News analysis shows Biden has spent 18 days in South Carolina since launching his campaign. By comparison, he was in Iowa for 61 days and in New Hampshire for 23 days.

Biden has also spent nearly $400,000 on South Carolina television and radio advertisements this month alone, much less than the seven-figure investments he made in Iowa and Nevada.

More of former Vice President Biden's interview with "Face the Nation" will air Sunday, February 23 at 10:30 a.m. ET