Tucker Carlson, perhaps the most popular podcast host on the American right, introduced his audience to James Fishback, a candidate for Florida governor, with a 76-minute interview in January. “Pretty soon, all winning Republican politicians will talk like this,” Mr. Carlson declared.

Mr. Fishback’s campaign did have a distinctive sound. On the trail and online, the candidate toyed with anti-Jewish ideas and engaged with influencers who presented Jews and members of other faiths as outsiders at odds with America’s Christian majority.

In the state’s primary last week, Mr. Fishback came in third, with 10 percent of the Republican vote. That showing was a source of both relief and disquiet for many of Florida’s Jews, who perceived Mr. Fishback to have put a target on their backs.

“People were very concerned by his campaign, by his campaign rhetoric, the attention that he drew, the support that he had from some of the most nefarious people of our time,” said Rabbi Efrem Goldberg of the Boca Raton Synagogue, a modern Orthodox congregation that counts 1,000 families as members.

On Primary Day, as Rabbi Goldberg drove his 79-year-old mother to the polls, they discussed the election and she remarked that in the past, “America wasn’t a comfortable place — or call it, ironically, a safe place — to say these sentiments out loud,” he recalled. Now, his mother had observed, rhetoric and associations that were once shameful had seemingly become common currency.

It has been an uneasy primary season for Jewish voters, with debates over Israel animating many races. But what happened in Florida went beyond that, and it wasn’t just one contest. In Florida’s Sixth Congressional District, the far-right influencer Dan Bilzerian waged an antisemitic primary fight against Representative Randy Fine — whom he labeled a “fat Jew” — and won nearly 19 percent of the Republican vote.

“He was overtly praising Hitler in his campaign,” said Aiden Harow, a 22-year-old from Boca Raton who recently graduated from Yeshiva University. (Mr. Fine, for his part, has faced criticism for a number of anti-Muslim remarks.)

Both Mr. Fishback and Mr. Bilzerian lost by wide margins, demonstrating that such appeals are not electoral assets. But their campaigns exposed the continued mainstreaming of anti-Jewish ideas and unsettled one of the largest Jewish populations in the country.

Florida is home to more than half a million Jews, and more newcomers have arrived in recent years — drawn in part by opportunities for remote work during the Covid-19 pandemic and by the state’s generous school voucher program, which has attracted families seeking to enroll their children in religious private schools.

Many of the newcomers have viewed Florida in the same way that Jewish arrivals to the state in previous generations did: as a particularly hospitable destination for those seeking to be part of a thriving Jewish community.

For some, the recent primary challenged these presumptions. Mr. Bilzerian had previously denied that six million Jews were killed during the Holocaust, claimed Jews were behind the 9/11 attacks and called for “exterminating Israel.” Days before the primary, he posted pictures of himself with supporters on social media with the caption, “District 6 understands the jewish problem.” This did not stop him from taking almost a fifth of the vote.

Mr. Fishback, by contrast, cast himself as merely a critic of Israel, not Jewish people. But his conduct complicated that claim. The same week he spoke to Mr. Carlson, he also spoke to Ella Maulding, a self-described Christian nationalist influencer. When asked to name “a big issue in America that Republican politicians won’t talk about,” Mr. Fishback didn’t hesitate: “The great replacement and white genocide. They’re both real, and I’m running for Florida governor to stop it.”

American Jews have experienced the consequences of such claims. The theory that a clandestine cabal of typically Jewish elites is seeking to replace the white race with nonwhite immigrants is a staple of antisemitic discourse.

In 2017, far-right demonstrators chanted “Jews will not replace us” at the Unite the Right rally in Charlottesville, Va. “HIAS likes to bring invaders in that kill our people,” a man wrote on social media in October 2018, referring to the Hebrew Immigrant Aid Society. “Screw your optics, I’m going in.” His attack that day on a Pittsburgh synagogue, which had recently held a HIAS-linked event, killed 11 worshipers.

In the span of eight years, an idea that had motivated the worst massacre of Jews on American soil had become part of the pitch for a political campaign.

In February, at an event at the University of Central Florida, Mr. Fishback told his audience that “if you wanted to set our kids up for failure, you would feed them the absolute goyslop in our cafeterias.” Goyslop is a slang term popularized by neo-Nazis to imply that Jews are enfeebling the non-Jewish masses by feeding them low quality processed food. Mr. Fishback had made a similar reference on social media days earlier.

He initially claimed ignorance of the word’s provenance — then kept using the term long after he was asked by reporters about its antisemitic connotations.

“He had a very small but very loud support base that was saying things that were pretty alarming,” Mr. Harow said regarding the Fishback campaign. “His messaging was very aggressive. We were getting phone calls, voice mails, text messages from dozens of different phone numbers, and no matter how many you blocked, you were just going to get more.”

Some of these messages framed Mr. Fishback’s candidacy in overtly religious terms. “Christ is King,” opened one, referencing a traditional Christian affirmation that has recently been weaponized by far-right activists on social media to assail Jews and others. As with the invocations of the “great replacement” and “goyslop,” the messaging took what began as an online meme and turned it into a selling point.

For some Jewish voters, the fact that both Mr. Fishback and Mr. Bilzerian were trounced in their contests was a positive sign. “I don’t believe there’s this groundswell of antisemitism in Florida,” said Alex Hochberger, a Jewish technology and marketing strategist in Hollywood, Fla., who cast the Fishback campaign as “an effort to build an influencer platform, not a serious candidacy.”

Sid Dinerstein, a former chairman of the Palm Beach County Republican Party and longtime resident of the state, was more focused on the upset victory of State Representative Angie Nixon, a critic of Israel and member of the Democratic Socialists of America, in the Democratic Senate primary. But his confidence in his state remained unshaken. “The two safest places for Jewish people are in Israel and Florida,” he said.

Joshua Sayles, vice president for external affairs at the Greater Miami Jewish Federation, said that “nobody thought for a second that James Fishback was going to win,” but that “some of his horrible rhetoric is making its way more and more into the mainstream.”

Still, Mr. Sayles said he remained “very comfortable” in his belief that “Florida voters reject extremists.”

Others, however, were less sanguine. “Be anti-Israel all you want, to a certain degree,” said Tammy Wagner, a 49-year-old registered Republican and database administrator who lives near Fort Lauderdale. “But being antisemitic, like that’s …” Her voiced trailed off. “It’s shocking to me that they got any votes. That makes me very nervous about our society.”

David C. Adams contributed reporting from Miami and Terry Spencer from Fort Lauderdale, Fla.