3 things to watch in South Carolina's Democratic primary

President Joe Biden is anticipated to take the lion's share of South Carolina's 55 delegates in the state's 2024 Democratic primary on Saturday.

But observers will be closely parsing the results as Democrats gauge signs of strength or weakness for the president with his base heading into a likely November rematch with former President Donald Trump as both candidates struggle with poor approval and favorability ratings.

South Carolina proved crucial to Biden, reviving his 2020 bid after disappointing finishes in Iowa and New Hampshire. He and his party then rewarded the state by shaking up the nominating calendar to have South Carolina go first this year.

This time, he faces two long shot challengers who have not yet gained much traction in the polls or with voters.

Here are three things to watch in South Carolina's primary.

How big is Biden's win, and who turns out

Biden is facing opposition from little-known Rep. Dean Phillips, D-Minn., and author Marianne Williamson, so anything less than a major victory by a major margin could spark hand-wringing from his Democratic supporters that he is already being rejected by some of the same voters he'll need to win in November.

But a solid performance could underscore party unity behind the president despite his polling issues.

Still, some Democrats have warned against reading too much into turnout or the size of Biden's expected victory as a barometer for his popularity -- noting that this year's primary is not "seriously contested" between major candidates, especially compared to Biden's 2020 win, when several serious contenders were fighting for the nomination.

Beyond raw turnout, though, some Democrats did say they're watching what kind of voters go to the polls, hoping that a cross-section of the party will show up for the president.

"I don't think you can reasonably measure the success of Biden by the numbers because it's not a seriously contested race," said South Carolina Democratic strategist Antjuan Seawright. "And so, this race is obviously a lot different, and there are a lot of dynamics in this race that did not exist in the last race. So I think a win is a win, but more or less, I think a diverse turnout is a big win for Biden. And when I say diverse, not just Black, but gender diverse, geographically diverse, diversity of thought is also important, too."

A test for Black voters -- and Jim Clyburn

Biden's 2020 South Carolina primary win was fueled largely by Black voters, who are a big part of the state's electorate. The demographic is likely to be key for him again this year and is historically key for Democratic victories.

But how many Black voters again cast ballots for Biden? Some polls show Trump ticking up his low support among Black voters and while Trump isn't running on Saturday, the results will give some indication of how many Black residents are still voting for Democrats compared to cycles past.

Biden, Vice President Kamala Harris and their campaign surrogates have sought to shore up support with those voters with multiple trips to South Carolina, considered a proving ground for politicians with Black voters.

Seawright said he expects Biden to perform well with Black voters but the results could be illuminating in other ways.

"I think more than anything, the campaign and the administration will have an opportunity to learn from the exit polls of the things that Black voters care about, in terms of the deliverables that this president has done," he said.

The primary will also serve to underscore the continued sway of Rep. Jim Clyburn, D-S.C., a member of House Democratic leadership who has been a big booster of Biden in the state -- including with a 2020 endorsement during what was then a low moment for Biden's campaign.

"I think he's proven his network and his net worth when it comes to this president in particular, and just Democratic politics," said Seawright, who is close with Clyburn.

What does it mean for Phillips and Williamson?

Meanwhile, Phillips and Williamson are not really registering in their own bids. Neither was able to gain much traction with voters against Biden in New Hampshire, where he only appeared as a write-in candidate but still won with more than 63% of the ballots -- and now they're facing off against him in a state more tailor-made to his strengths.

One recent poll tracked by 538 showed Biden ahead by more than 50 points.

Still, their ongoing campaigns serve as a contrast to Biden -- and an annoyance to many of his allies -- as he pushes to rally the party entirely behind him while Phillips argues the electorate needs a new, younger candidate to take on Trump.

Some party operatives said they are eager for a knockout blow to help persuade Phillips and Williamson to exit the race.

"More than anything, I hope that Dean Phillips and Marianne Williamson ... will understand the urgency and importance of unity going forward after the South Carolina primary," Seawright said.