WASHINGTON (Reuters) - With each passing day, South Carolina looms larger as perhaps Joe Biden’s last line of defense if he hopes to secure the Democratic presidential nomination next year.

FILE PHOTO: FILE PHOTO: U.S. Democratic presidential candidate and former U.S. Vice President Joe Biden speaks during a forum held by gun safety organizations the Giffords group and March For Our Lives in Las Vegas, Nevada, U.S. October 2, 2019. REUTERS/Steve Marcus

While polls show the former vice president trailing in other early voting states such as Iowa and New Hampshire, South Carolina - with its sizable African-American population - remains one place where Biden holds an undeniable advantage.

But sensing potential weakness, Biden’s rivals from liberal standard-bearers Elizabeth Warren and Bernie Sanders to moderate challengers such as Pete Buttigieg to black senators Kamala Harris and Cory Booker are all looking to take that away.

African-American support will be crucial to win the party’s presidential nomination. With black voters comprising two-thirds of the Democratic electorate in South Carolina, the state offers the first major test of candidates’ strength with the key voting block.

The most recent poll in the state by Winthrop University had Biden taking 46 percent of the black Democratic electorate, but also showed that 44 percent might change their mind before the state’s primary on Feb. 29.

“I’m getting calls from people who are Biden supporters who now want to hedge their bet and support somebody they think can actually win,” U.S. Senator Cory Booker of New Jersey, who has made South Carolina central to his presidential bid, told reporters in Washington this week.

Defeating Biden in the state will not come easy. Polls have him averaging more than a 20-point lead over the rest of the field, while more than 85 legislators and pastors have endorsed him, dwarfing endorsements for any of his rivals.

Bolstered by the eight years he served as No. 2 to Barack Obama, the first black U.S. president, Biden has deep roots with black politicians and clergy in the state and nationally.

“He’s familiar,” said Joe Darby, senior pastor at African Methodist Church in Charleston, who added that Biden has spoken at his church banquet several times. “He doesn’t wait until an election year to show his face.”

Biden, Warren, Sanders and seven other Democratic presidential contenders will head to South Carolina this weekend to present their criminal justice plans at the historically black Benedict College in Columbia, South Carolina.

WIN EARLY

Most of Biden’s rivals are starting from scratch in the state.

But they are all betting a stronger-than-expected showing in Iowa, the state that will kick off the nominating contest in February, will win them a hard look in South Carolina, just as Obama’s 2008 performance in Iowa helped draw black voters away from presumed front-runner Hillary Clinton in later contests.

South Carolina is the fourth contest on the Democratic calendar, coming after Iowa, New Hampshire and Nevada.

Older black voters, who are among the most reliable in the party, tend be more pragmatic than white progressives, focusing less on policy and more on whether a candidate can be successful, said Theodore Johnson, an expert on race and politics at the Brennan Center for Justice.

“You have to prove you can win white voters,” Johnson said, “because that proves you can win the general election.”

That may part of the calculation of Warren, who has made fewer trips to South Carolina than Iowa and New Hampshire.

Though she has struggled to add black voters to her expanding base of support among women, college-educated whites and young people, Warren’s campaign believes her populist focus on income inequality and structural change can help her eventually resonate.

Warren has also been the candidate running the most Facebook ads that mention variations of the words “black” or “African American” since May, according to a Reuters analysis of ad data gathered by the Online Political Ads Transparency Project.

The ads have focused on Warren’s pledge to make public college tuition-free and restore historically black colleges and universities.

Warren’s progressive rival, U.S. Senator Bernie Sanders, meanwhile has concentrated on criminal justice reform, said Michael Wukela, the campaign’s communications director in South Carolina. Sanders wants to ban for-profit prisons, abolish the death penalty and tighten rules and penalties for police misconduct.

Since he is more popular with younger voters, his campaign also hopes to motivate those voters to speak to their older relatives, Wukela said.

“It’s not just saying we need you to show up on election day. It’s saying we need you to show up on Thanksgiving, when you’re back home.”

RURAL VISITS, FAITH APPEAL

Black support has been also elusive for Booker and Harris, both black politicians. Both have made visiting rural black communities a key to their strategy and visited the state more than any major candidate in the field.

Harris’ campaign believes she is well positioned to pick up many of Biden’s supporters should his campaign falter, said a campaign aide who requested anonymity to speak frankly.

“Kamala Harris doesn’t need to be told what the concerns of the black community are,” the aide said.

Like Biden, both have hired faith coordinators to connect with local pastors, who act as campaign conduits to their congregations.

Aaron Bishop, a pastor who is overseeing Booker’s faith outreach program, said Booker’s embrace of his own faith – including his use of scripture when speaking during Sunday services – has brought him new supporters every time he has appeared at a church gathering.

Buttigieg, the mayor of South Bend, Indiana, may face the toughest uphill path among the top-tier Democratic contenders in the state.

Buttigieg has clashed with black activists in South Bend over economic and law enforcement issues, and a senior campaign aide acknowledged that some churchgoing African-Americans in South Carolina are uncomfortable with the fact that Buttigieg is openly gay and has a husband.

Only 56% of African-Americans said they have a favorable view of Buttigieg in a recent Reuters/Ipsos poll, compared to 78% for Sanders, 76% for Biden, and 68% for Warren. That represented the lowest favorability rating among top 10 Democratic candidates, though it is still higher than Trump’s 23% favorability among black voters.

Buttigieg is counting on success in Iowa and New Hampshire to persuade those voters to give him a second look, the aide said.

Ultimately, the race for black voters may come down to electability, said Darby, the Charleston pastor and Biden supporter who urged candidates to talk less about sweeping proposals and more about how they would beat Trump next year.

According to a Oct.18-22 Reuters/Ipsos poll, 18% of African Americans approve of Trump’s performance, while 76% disapprove.

“I appreciate good policy position,” Darby said. “But you don’t redecorate the house while the house is blazing.”