South Carolina primary 2020: When is it, how does it work, how many delegates?

Former Vice President Joe Biden still holds a lead in the upcoming South Carolina primary, but the lead he once enjoyed has shrunk dramatically in recent weeks.

Biden, who has said he considers Saturday’s primary a “firewall” for his campaign, blames his drop in the polls on billionaire Tom Steyer.

Steyer has spent a reported $10 million in the state on TV ads and digital ads on Facebook and YouTube.

“What’s happening is you have Steyer spending hundreds of millions, tens of thousands of dollars, millions of dollars, out campaigning there,” Biden said Sunday on CBS News’ “Face the Nation.”

Biden went on to say he assumed Steyer’s spending was "part of the reason why those numbers are down."

"But I don't know," he said.

Steyer’s rise in polls has qualified him to participate in Tuesday’s Democratic debate.

Vermont Sen. Bernie Sanders won the Nevada caucuses on Saturday afternoon, followed by Biden with 21% and former South Bend, Indiana, Mayor Pete Buttigieg with 14%.

Here’s what you need to know about the South Carolina primary.

When does the South Carolina primary take place:

Voters in South Carolina will go to the polls on Saturday.

Who can vote:

South Carolina has an open primary system. That means that anyone registered to vote may cast a ballot in either party's primary.

What time do the polls open:

The polls open at 7 a.m. ET and close at 7 p.m. ET.

How many delegates:

The Democrats will be awarding 63 delegates on Saturday. Fifty-four of those delegates are pledged to the winner of the primary.

The other nine are unpledged delegates, or superdelegates.

Who is ahead in the polls:

Biden leads in all major polls, but not by as much as he once did. Both Sanders and Steyer have cut into Biden’s lead. According to the Real Clear Politics average of polls, Biden is ahead by 3 points in the state at 24.5%. Sanders follows with 21.5 percent and Steyer has 16.5 percent.

Following are Buttigieg at 10.8%, Massachusetts Sen. Elizabeth Warren at 9.5%, Minnesota Sen. Amy Klobuchar at 6.5% and Hawaii Rep. Tulsi Gabbard at 1.8%.

Former New York City Mayor Michael Bloomberg is not on the ballot in South Carolina.

What about Republicans:

The South Carolina Republican Party's executive committee decided not to hold a 2020 Republican presidential primary.

The 50 Republican delegates will go to President Donald Trump.