One way to defeat an insult is to proudly adopt it as an identity. History is rich in stories of abusive words like “Tory” (originally meaning robber) or “queer” being transformed into badges of honor. Joe Biden might want to do the same in response to a feature article journalist Olivia Nuzzi has published in New York magazine describing the former vice president as running a “zombie campaign.” Nuzzi does an expert job of describing why Biden is “the least formidable front-runner ever,” and yet also conveys his genuine skills as a candidate. Like a zombie, Biden can be faltering, inarticulate, and even brainless, while still remaining strangely durable—indeed, virtually indestructible.

Biden’s undead campaign keeps trudging forward, despite his gaffes and attacks from other candidates, the press, and protesters, all eager to remind voters of Biden’s unsavory past—his opposition to busing, the sidelining of Anita Hill, and his vote for the Iraq War. Even after the recent upsurge in support for Elizabeth Warren, Biden remains the front-runner.

There’s a tension between Biden’s persistent status on top of the polls and the sense conveyed by many reporters such as Nuzzi that his campaign is in trouble. As Nuzzi notes, the polls are contradicted by the funds being raised, a problem also flagged by The New York Times, which reported that big donors were getting nervous about Biden. Nuzzi observes that “though he’s the party Establishment’s obvious exemplar, he can’t seem to raise any money—spending more in the last quarter than he brought in and moving into the home stretch with less than $9 million in the bank (roughly a third of what Elizabeth Warren or Bernie Sanders has on hand). For political reporters, marveling every day at just how well this isn’t going, watching Biden can feel like being at the rodeo. You’re there because on some level you know you might see someone get killed.”

Even on the polling front, the news is much less good when you look at the early states like Iowa, New Hampshire, and Nevada, where Biden’s lead has either disappeared or narrowed. As Nuzzi writes, “The path to a collapse seems clear: Biden loses in Iowa and New Hampshire, where his leads have been steadily declining for months and where, recently, Elizabeth Warren has overtaken him, and then, as a result, loses his sheer aura of electability, too.” To counter this nightmare scenario, Biden’s campaign is arguing that it can weather losing in the early states until it gets to South Carolina, where Biden is popular among African American voters, and begins to more broadly win pluralities in the remaining states.

This is a risky gambit, aiming at a thin victory. But it’s plausible. Biden is helped by the fact that the support he has, while low compared to other front-runners’, is durable. There’s a constituency for his brand of centrism, a good-natured, folksy, empathetic, and nostalgic vision of politics as glad-handing. As polling guru Nate Silver notes, Biden remains a contender because many Democratic “voters are moderate, or ‘somewhat liberal’ rather than ‘very liberal’, and prefer Biden’s somewhat liberal, Obama-ish policy positions to Warren/Bernie/etc.”

Biden’s stranglehold on those moderate or somewhat liberal voters is what keeps him viable. He’s helped by the fact that none of many centrists running in the primaries has broken out of the single digits. One of the most plausible ways that Biden can be derailed is if another centrist surged.

Among the crowded field of contenders, Pete Buttigieg is best placed to challenge Biden as the centrist leader. In many ways, Buttigieg is Biden’s opposite: young, articulate, and intellectual. If Biden is the zombie of the race, Buttigieg is the whiz kid. He’s also been much better at fundraising than Biden, almost in the same league in dollars collected as Bernie Sanders and Elizabeth Warren.

However, while Buttigieg is becoming competitive in the early states, he still hits a brick wall in South Carolina, where he’s currently polling at 3 percent. Among African American voters in South Carolina, Buttigieg does even worse, getting 1 percent. By contrast, Joe Biden gets 39 percent of the black vote in that same poll. Buttigieg’s problems in South Carolina illuminate why it’ll be difficult for him to elbow out Biden as the top centrist in the primaries.

The New York Times published an article on Sunday investigating the role homophobia in the black community might play in Buttigieg’s low support, given he’s the only openly gay man in the race. According to the Times, “The Buttigieg campaign held focus groups [in South Carolina], which suggested ‘being gay was a barrier’ for him, according to an internal campaign memo that surfaced last week.”

The treatment of homophobia in South Carolina as if it were an exclusively black problem is ridiculous. The Times fails to consider whether homophobia among socially conservative Southern white Democrats might also be limiting Buttigieg’s support. Further, while the Times acknowledges that there might be other factors at work, like low name-recognition, none of these are dwelt on.

While homophobia is undeniably a problem, class is just as big a hurdle for Buttigieg. Biden’s strength is that he pulls in voters from across the economic spectrum. Sanders also has an advantage in that he is very popular among low-income voters. Buttigieg’s weakness is that he’s most popular among the well-to-do.

An Emerson poll from August usefully broke down the class divide. Thirty-nine percent of Biden supporters make less than $50,000 per year, as against 60.4 percent of Sanders supporters and 7.1 percent of Buttigieg supporters. Conversely, 18.8 percent of Biden’s supporters make more than $100,000 a year, as against 5.9 percent of Sanders supporters and 56.8 percent of Buttigieg supporters.

While Biden and Buttigieg are both positioning themselves as centrists, the actual base of their support is very different. Buttigieg’s pitch is winning over professional upper-middle-class voters, but not the working poor. As long as that remains true, Biden will continue to dominate among centrists.

Whatever else you want to say about Joe Biden, he has built a following in the Democratic Party that brings together key constituencies in the manner of Barack Obama in 2008 and Hillary Clinton in 2016: He has support among upper-middle-class professionals as well as working-class people of color. Buttigieg has gained traction on only one part of that equation, the numerically much smaller one. Biden is running a deeply flawed campaign, but it’s unlikely that the whiz kid will be the one to finish off the zombie.