New polls show Joe Biden holding onto his lead in the S.C. Democratic presidential primary, bolstering the case that the former vice president could come out of the South's first primary Saturday with a crucial push for Super Tuesday.

Biden holds double-digit advantages over Vermont Sen. Bernie Sanders and billionaire activist Tom Steyer, according to polls released Thursday from Starboard Communications and Monmouth College.

His lead is more narrow in a Post and Courier-Change Research poll that has Sanders within the margin of error to Biden.

Biden's continued hold atop S.C. polls comes after a second-place showing in Nevada on Saturday, his first finish among the leaders in the 2020 early-voting states.

Strong support among black voters, who cast about 60 percent of S.C. Democratic primary ballots, continues to carry Biden in the Palmetto State — long considered his firewall after stumbles in other early-voting states.

His African American voter backing in South Carolina ranged from 34 percent to 57 percent in the new polls, well ahead his rivals. Some of the polling came before Biden received an endorsement Wednesday from U.S. Rep. Jim Clyburn, the state's most prominent black politician.

Sanders, the national front-runner, continues to push hard in South Carolina after winning the past two Democratic races, in New Hampshire and Nevada, and coming in a close second in Iowa. He is hoping to improve his support among African American voters over his 2016 bid, which included a lopsided loss to Hillary Clinton in the 2016 S.C. Democratic primary.

Steyer has concentrated his campaign efforts in South Carolina, his best hope for getting a top-tier showing after averaging a sixth-place finish in the first three races.

Many recent S.C. polls have found more than 10 percent of voters undecided just days before the primary on Saturday.

In eight previous Post and Courier-Change Research polls of the 2020 S.C. Democratic race taken during the past year, Biden's margin over his challengers has ranged from a high of 31 percentage points in May to a low of of 5 percentage points last month as Sanders and Steyer surged. He has never trailed in any of the 34 polls taken in the state tracked by Real Clear Politics in the past year.

The latest Post and Courier-Change Research poll has Biden's lead at just four percentage points. He received 28 percent to Sanders' 24 percent and Steyer's 16 percent. Warren followed at 12 percent and Buttigieg at 11 percent.

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Some of the new results have Biden with the larger leads he enjoyed for much of 2019.

Starboard, a Lexington political consulting firm known for working with Republican candidates, found in a one-day poll on Wednesday that Biden held 40 percent of support, with Steyer at 12 percent and Sanders at 11 percent. Warren and Buttigieg were at 9 percent each.

More than half of the 1,102 likely S.C. primary voters that Starboard surveyed said they watched the debate in Charleston on Tuesday.

Monmouth had Biden at 36 percent, doubling up Sanders (16 percent) and Steyer (15 percent). Warren and Buttigieg were farther back at 8 percent and 6 percent respectively.

Minnesota Sen. Amy Klobuchar, who has struggled to gather black voter support in South Carolina, failed to get past 6 percent in any of the new polls. Hawaii congresswoman Tulsi Gabbard has lagged at or near the rear of the field in S.C. surveys.

Other polls in the past week also showed Biden ahead in South Carolina as an uncertain future awaits his campaign when 14 states hold primaries next Tuesday.

A Clemson University poll released Wednesday that had Biden at 35 percent to Steyer at 17 percent and Sanders at 13 percent. Biden's lead was a bit tighter in a Winthrop University poll released last week before his second-place finish in Nevada. He held a 5-point advantage over Sanders in that poll.

The Post and Courier-Change Research poll of 543 likely S.C. Democratic voters primary voters taken Feb. 23-27 had a margin of error of plus or minus 5.1 percent.

The Monmouth poll of 454 likely S.C. Democratic voters primary voters taken Feb. 23-25 had a margin of error of plus or minus 4.6 percent.

Starboard poll of 1,102 likely S.C. Democratic voters primary voters taken Feb. 26 had a margin of error of plus or minus 2.82 percent.