GREENVILLE, South Carolina — Democrats in South Carolina are warning Joe Biden and his campaign against resting on their laurels in a key primary state where he has campaigned off-and-on for more than 30 years.

Biden's campaign has sought to manage Palmetto State expectations ahead of the Feb. 29, 2020 Democratic primary. It's told reporters their strategy to secure the 2020 Democratic presidential nomination hinges on South Carolina and a slew of Super Tuesday states, forgoing Iowa and New Hampshire to rivals such as Massachusetts Sen. Elizabeth Warren.

A Winthrop Poll released this week found Biden retains about 37% support among likely Democratic voters in South Carolina, with 46% support among African American Democrats, who comprise a majority of the primary electorate. His closest competitors in the state are Warren at 17%, Vermont Sen. Bernie Sanders at 8%, and California Sen. Kamala Harris at 7%. The Winthrop survey roughly mirrors polling averages compiled by RealClearPolitics.

While Biden's numbers look good now in South Carolina, Hillary Clinton enjoyed similar momentum there in 2007 before her Senate colleague, President Barack Obama of Illinois, became the first African American to win an Iowa caucus. After Obama won almost 38% of the Iowa vote on Jan. 3, 2008, his polling in the "First in the South" primary soared, boosted in part by the state's active black community, and setting him on the road to the White House that November.

Since announcing his third White House bid in April, Biden has been to South Carolina five times, most notably for the state's Democratic Party convention after touting his work with known segregationists in the Senate during a private fundraiser. But Democrats in Greenville County, one of the many South Carolina counties that overwhelmingly backed President Trump in 2016, think his campaign needs to invest more resources in the Upstate if he wants the state's 60-plus delegates. The Biden campaign should, in this view, focus there rather than simply channeling all his energy in the bluer, more diverse areas around Columbia and Charleston.

During the Greenville County Democratic Party's September breakfast and meeting, a Biden organizer was lightly mocked for not knowing when his team was opening its office — they only received the keys to the premises last week. Like other operations, the Biden camp has been launching canvassing drives and hosting phone banking sessions from the party's headquarters in town.

"You don't know? The primary's almost over," the man joked.

Ruth Todd, a 57-year-old retired photographer from Travelers Rest who was at the meeting, told the Washington Examiner it was "kind of a big deal" the Biden campaign was slowly rolling out its ground game since he's a top-tier candidate. His organizing efforts can be contrasted with that of Harris and New Jersey Sen. Cory Booker, both African American contenders who've dominated the grassroots network since declaring their respective candidacies.

South Bend, Indiana, Mayor Pete Buttigieg has been active in the region, Todd said, reflecting his attempts to be seen as a serious centrist backup should Biden's appeal wane. Buttigieg has so far struggled with African American voters, but perhaps sees an opportunity to pick up white Democrats outside South Carolina's Lowcountry and Midlands, visiting the Upstate twice during his six swings through the state.

"The most present to me that I see is Pete's campaign, Kamala's campaign. Just started seeing Biden's campaign, so they're not out there as much," she said, adding former Texas Rep. Beto O'Rourke also had a high profile. "They think they have the state locked up."

To Todd, voters care more about personality than politics, which is why she places a premium on "having a presence" and "making people excited." She said Biden's age is a disadvantage when trying to enthuse Democrats, including some older voters who "know their own limitations" and "mental capacity."

Amanda McDougald Scott, the committee's candidate development coordinator who encouraged attendees at the meeting to consider their options for the party's nominee with an open mind, agreed she "hadn't seen him here as much," but understood given the demographics. She did, however, mention the former vice president visited Rock Hill in August for a town hall.

Whitney Wright, second vice chairwoman of the committee and secretary of its black caucus, said the Biden campaign had been busy, hosting debate watch parties and a United Against Hate rally in Anderson over the summer in response to Vice President Mike Pence's trip around the same time. She referred to the faction of Democratic voters "who are Team Biden no matter what you say" but additionally alluded to Buttigieg's high visibility.

"You don't necessarily have to have an office space to make that impact if you're getting out there and getting to know people," she said.

But Wright added, "I do feel like people need to pay attention to the Upstate in general and to Greenville, and the reason I say that is because there's so much going on here."