Twelve years ago, Rush Limbaugh, who had not yet received the Presidential Medal of Freedom, urged the listeners of his enormously popular and very conservative talk-radio show to vote for Hillary Clinton in the Democratic primaries. In the patchwork process that is employed to nominate Presidential candidates, more than a dozen states have open primaries, which allow registered voters to participate in either contest. Limbaugh wanted Clinton’s close but seemingly losing fight with Barack Obama to go on for as long as possible, on the theory that a protracted battle would weaken the eventual nominee. He called the plan Operation Chaos. Limbaugh didn’t think that Clinton was necessarily the weaker of the two candidates—in fact, he ultimately concluded that Obama was; by May, 2008, he was pushing his fans to vote for the senator from Illinois. “Barack Obama has shown he cannot get the votes Democrats need to win—blue-collar, working-class people,” Limbaugh said. “He can get effete snobs, he can get wealthy academics, he can get the young, and he can get the black vote, but Democrats do not win with that.”

Karen Martin, a freelance editor and pet-sitter who lives in Spartanburg, South Carolina, believes that her plan is more strategic than chaotic. Martin is the creator of Trump 2-29, which is encouraging Republicans to vote for Bernie Sanders in the state’s upcoming Democratic primary, on February 29th. “We’re really mad,” Martin told me recently, referring to her fellow-conservatives. “Mad at how our President has been treated for the past several years and wanting to do something now.” Voting for Trump isn’t an option: South Carolina’s Republican primary was cancelled in October, out of deference to the President. (“With no legitimate primary challenger and President Trump’s record of results, the decision was made to save South Carolina taxpayers over $1.2 million and forgo an unnecessary primary,” South Carolina’s G.O.P. chairman, Drew McKissick, announced in a statement at the time. A former Republican state representative sued to block the cancellation but lost in court.) Obama’s former Vice-President, Joe Biden, was expected to perform well in South Carolina; Martin wanted to vote for someone who could ruin it for him. As Iowa neared, she said, “We decided it’ll be Bernie.” Martin doubts that Sanders will ultimately be the Democrats’ nominee—though, if that happens, “It would be a great lesson in American Civics 101,” she said, adding, “To have those final debates be between an avowed socialist and a capitalist with the economic record that President Trump does, that would be really a contrast to see. Bernie makes it poetic.”

The South Carolina Republican Party has no official involvement in Martin’s efforts, but it hasn’t discouraged them, either. The executive director of the South Carolina G.O.P., Hope Walker, issued a statement acknowledging the existence of “activists that may decide to participate in the open Democratic Presidential Preference Primary” and explaining that the Party “has taken no official stand on this matter.” Meanwhile, Nathan Leupp, the chairman of the Greenville County Republican Party, told the Charleston Post and Courier, “I think we can easily affect the outcome. This is going to catch on like wildfire.” Leupp told me that he had talked not only to local activists but to the five other upstate-county G.O.P. chairmen about the plan; they concluded that it would be best for “the grassroots activists to make this push,” he said. (The Post and Courier story mentioned a planned press conference; after the story ran, Leupp said, the effort got so much attention that “we didn’t need a conference at that point.”)

Independently from Martin, a political and public-relations consultant from Greenville named Christopher Sullivan has launched a campaign that nods more explicitly to Limbaugh’s influence: Operation Chaos 2020. “We’ve put up a Web site, and we’re doing some digital work and communicating with our members and supporters,” he told me. Operation Chaos 2020 flyers were handed out at a Party meeting and garnered some attention on Twitter—there are plans for radio advertising, too, Sullivan said. Both the flyers and the Web site note that the effort is a project of the Conservative Defense Fund, the name of which may suggest a large organization; Sullivan is the chair of the group and, he said, its only full-time employee. (Karen Martin told me, of her own campaign, “The other day somebody asked, ‘So how much money is behind this effort?’ And I had to laugh. It’s when I can, in between dog-walking.”) But Sullivan is optimistic that even a modestly funded campaign could have real effects. He noted that, in South Carolina primaries, Republicans typically turn out at twice the numbers of Democrats—so even a small percentage of Republican crossover voters could be decisive in a reasonably close race.

Unlike Martin, Sullivan is not pushing any particular candidate. “One of the things is that the Democratic primary is in such disarray of their own making that it’s kind of hard, even at this late date, to know exactly which candidate is gonna be the best one to choose,” he said. “Six weeks ago, Joe Biden was the front-runner, and everybody was saying he was assured of the nomination. And now he’s dropping like a rock. It might be the best vote would be to prop up Joe Biden.” Sullivan set up a poll on the Operation Chaos 2020 Web site asking “which crazy Democrat candidate” participants in the operation should vote for. Late last week, Sanders was winning in a landslide, but, over the weekend, thousands of new votes came in for Elizabeth Warren. “I think her socialist policies would be a big loser in the general election, so I can see why Republicans would want her to be at the top of the ticket,” Sullivan told me. It may be that deciding which candidate is the least likely to beat Trump is no easier than deciding which is most likely to do so.

The kind of voting that Martin and Sullivan are pushing for is often called party raiding, and it has been around for a long time. Measuring its effect is difficult, but it is usually thought to be very small. (In 2008, when Limbaugh was pushing Clinton, some Obama supporters were convinced that bad-faith Republican voters had won the Indiana primary for her, but this was disputed.) That said, South Carolina in 2020 is a “perfect storm of crossover-voting incentives,” according to Josh Putnam, a political scientist based in Wilmington, North Carolina, who runs the election-consulting firm FHQ Strategies. Putnam pointed to the earliness of the primary and the absence of a G.O.P. contest in the state and noted that, in South Carolina, unlike in many other states, primary participants don’t have to publicly proclaim that they belong to the party whose primary they are voting in. It may not hurt that President Trump has openly encouraged party raiding: at a rally in Manchester the night before the New Hampshire primary, Trump said, “So I hear a lot of Republicans tomorrow will vote for the weakest candidate possible of the Democrats. Does that make sense? You people wouldn’t do that!” (New Hampshire has a semi-open primary: those who are not registered as a member of a party can vote in either race.) Trump added, “My only problem is I’m trying to figure who is their weakest candidate—I think they’re all weak!” The South Carolina effort “has the potential to not only affect the race but how the field of candidates continues to winnow,” Putnam said. “The final remaining variable is promotion.”

Martin has been trying to spread the word on Facebook, where, on the official Trump 2-29 page, you can see debates about the plan unfold in real time. “Bernie is leading in the polls,” a Charleston resident named Sheri Irwin wrote. “Why on earth would we vote for him?” A man named Paul Fallavollita responded by highlighting South Carolina’s importance to Biden, adding, “A lot of corporations and banks have said they’ll pull their donations away from the Democratic Party if Bernie is the nominee. Here’s an opportunity to starve them of funds. Plus, if Bernie wins most of the primaries and the DNC cheats him, his voters will stay home in November.” Irwin wasn’t convinced. “This is how we got the usurper Obama,” she wrote. Then another South Carolina voter, Clark Mccauley, chimed in. “Democrat party don’t want Bernie that’s why we need to vote for him,” he wrote. “He is the craziest.” Lisa S. Marie wasn’t sold. “Good to know that the Tea Party is now pro abortion and for socialism,” she commented. “Good luck selling that!”