Four years ago, Senator Jon Ossoff was sworn in using a book of Hebrew scripture as he proudly became Georgia’s first Jewish senator.

Now, some of his fellow Jewish Democrats have not only turned on him — they are also encouraging the most formidable Republican who could challenge him in next year’s marquee Senate race, Gov. Brian Kemp, to do just that.

“As a bipartisan group of leaders in the metropolitan Atlanta Jewish community, we humbly ask you to consider running for the United States Senate in 2026,” read a private mid-December letter to Mr. Kemp from some of the state’s major political donors and Jewish community leaders, which was reviewed by The New York Times.

“Should you decide to run in the 2026 election,” the letter said, “you would find no better friends, more loyal allies or stronger supporters than us and our community.”

The letter, which came after Mr. Ossoff voted to block certain weapons transfers to Israel and criticized its conduct of the war in Gaza, was a striking rebuke of a senator who has highlighted his Jewish identity and voted for billions of dollars in security assistance to Israel.

And it vividly illustrated how the war continues to scramble and threaten the Democratic coalition, even as party officials strain to mount a unified response to President Trump.

“I took great pride to see a young Jewish man find the successes that he has,” said Isaac Frank, a Democrat from a prominent Atlanta Jewish family who signed the letter to Mr. Kemp. “I just feel like he’s somewhat disconnected from where our community is, given post-Oct. 7.”

For a small but potentially influential group of American Jews, there are signs that the Oct. 7, 2023, attacks on Israel and a surge of antisemitism in the United States reordered their priorities and pushed them away from the Democratic Party, a shift that has endured through the first weeks of the Trump administration, according to interviews with nearly two dozen Jewish community activists, donors and officials in Georgia and around the country.

Long loyal to Democrats, these voters often oppose Republican domestic policy and detest Mr. Trump and his elevation of far-right figures with a history of antisemitic remarks. Some view his proposal to take over Gaza as outlandish or immoral, and are no fans of Israel’s right-wing government.

But on issues that have felt especially urgent to them since Oct. 7 — defending Israel and cracking down on domestic antisemitism, especially on college campuses — they increasingly see Republicans as more supportive.

A report released on Wednesday from the American Jewish Committee found American Jews slightly more likely to disapprove of how the Democratic Party was responding to antisemitism than of how the Republican Party was. Majorities of Jews disapproved of both parties’ approaches.

The survey, conducted late last year, found Jews to be equally worried about antisemitism on the “extreme political right” and the “extreme political left.” But that was a notable shift from four years earlier, when Jews were much more likely to say the extreme right represented an antisemitic threat.

“They don’t quite know where they belong, and I don’t think there’s an easy answer on either side,” said Deborah E. Lipstadt, who was the Biden administration’s special envoy to monitor and combat antisemitism, speaking in particular of “strongly committed, identifying Jews.” She added, “I don’t think personally I’ve ever seen such a time, in terms of, ‘Where do we stand?’ or, ‘where’s our political home?’”

The war in Gaza has divided Democrats since it began.

Many Arab American, Muslim and younger progressive voters, including some Jews, were furious with the Biden administration’s strong backing of Israel. Other Jews, often older and more moderate or conservative, thought the administration was not supportive enough.

“The Jewish community is not a monolith,” Mr. Ossoff said in the first of three phone calls with The Times on Thursday. “These are complex national security and foreign policy issues, and the breadth of Jewish American public opinion reflects that.”

The sparse polling available suggests that many Jews supported former Vice President Kamala Harris last year, hoping to protect abortion rights and democratic norms.

Ilan Goldenberg, who led Jewish outreach for the Harris campaign, said most Jews viewed Mr. Trump as “anathema” to their values. But many, he said, expressed a heightened nervousness.

“The level of importance of Israel went up — is probably still up,” he said.

“If the Republican Party was the Republican Party of 15 years ago,” he added, “you might have seen more movement.”

Republicans see opportunities to win over more Jewish voters in major contests next year. But in today’s party, the perpetual question is whether the candidate who emerges from a primary can appeal to swing voters.

“If Marjorie Taylor Greene is the Republican nominee, I can’t vote for her,” said State Representative Esther Panitch, a Democrat and Georgia’s only Jewish state legislator, referring to the far-right lawmaker who has pushed antisemitic conspiracy theories.

But Ms. Panitch did not rule out supporting Mr. Kemp if he ran.

“Kemp has done things that I am fighting against every day,” said Ms. Panitch, pointing to his signing of a six-week abortion ban. “But it is a different level of betrayal that Ossoff has committed.”

Cody Hall, a Kemp spokesman, declined to comment.

Navigating a community that’s ‘reeling and in shock’

No one, Mr. Ossoff suggests, should have been surprised by his stance.

“I expressed in the early weeks of the war my concern with the level of civilian harm and wide-scale destruction in Gaza,” he said Thursday. “I have strongly supported security assistance to Israel since Oct. 7, but make no apology for opposing the reckless killing of noncombatants.”

“We are in a moment in history,” he added later, “where the protection of civilians, the law of armed conflict and basic humanitarian values are in crisis.”

His view is well within the Democratic mainstream nationally and in Georgia, where there is also a significant Muslim population, and where many Black voters and pastors have embraced the Palestinian cause. Some Jewish officials, too, say he reflects many in the community.

“What I see is a Jewish community, both here in Georgia and nationally, that is deeply concerned about hostages and that is also deeply concerned about civilian casualties” among Palestinians, said Emily Kaiman, an Atlanta-based official with J Street, a liberal pro-Israel group, which supports Mr. Ossoff.

For Mr. Ossoff’s Jewish critics, the issue is not whether he has been consistent — it is whether he has been sufficiently outspoken about Israel’s security and rising antisemitism in the United States.

“When all this antisemitism was going on in this state and the Jewish community needed leaders, Jon didn’t, you know, put on his kipa and tallis and come to shul and seek us all and embrace us all and say, ‘Hey, I’m here with you guys,’” said David Lubin, a Democrat from Dunwoody, Ga., who ran unsuccessfully last year in a State Senate primary, referring to Jewish religious garb.

Mr. Lubin’s 20-year-old daughter, Rose, was killed while serving as a Border Police officer in Israel. Mr. Ossoff sponsored a resolution in her memory — but only, Mr. Lubin noted, after he had reached out and asked the senator “very strongly” to do so.

Asked if that was his recollection, Mr. Ossoff replied, “I was proud to champion the passage of a resolution in the United States Senate honoring this Georgian who was killed in the line of duty.”

Mr. Ossoff stressed that he cared “deeply” about Israel’s security and understood firsthand the intensity of antisemitism: “I need merely to open my mail,” he said. “I am a target of vicious antisemitic attacks every single day.”

He has met with the families of Israeli hostages, addressed community events focused on Israel and antisemitism, and voted to secure funding for Israel. He said he had spent part of Thursday meeting with the father of an Israeli hostage, and he emphasized that he grasped the community’s pain.

“The Jewish community has been reeling and in shock and in fear since Oct. 7,” he said in a third call, “fearful of the rise in antisemitism, fearful for Israel’s security and loved ones and friends and family in Israel. And I share and feel deeply that same shock, that same outrage, and that is why I supported unprecedented security assistance to the state of Israel.”

His opposition to certain weapons transfers, he suggested, was “based upon my assessment of America’s national interest and the core values that are at stake.”

Those failed measures, introduced by Senator Bernie Sanders, independent of Vermont, were opposed by the Biden administration and were never expected to pass.

But in Atlanta, the backlash was real.

Roughly 50 Jewish groups and synagogues — including the Temple, a Reform synagogue, steeped in civil rights history, where Mr. Ossoff had his bar mitzvah — signed a letter rebuking Mr. Ossoff and Senator Raphael Warnock for their votes.

Also included among the signatories were groups with national footprints, like the Anti-Defamation League of the Southeast, the Atlanta chapter of the American Jewish Committee and AIPAC.

“Can you imagine, all these Jewish organizations agreeing on something in a strong letter, a strong proclamation? Absolutely stunning change,” said Norman Radow, one of the state’s largest Democratic donors, who signed the separate letter to Mr. Kemp and has floated the idea of supporting a primary challenger to Mr. Ossoff. “That’s a reflection of Oct. 7.”

Feeling ‘abandoned’ but willing to talk

To Mr. Ossoff’s Jewish fans, some of whom signed a counter-letter in support, the pushback has been bewildering and disproportionate. They argue that the criticism from Jewish groups does not reflect the views of rank-and-file voters.

Robert Wittenstein of Dunwoody, an Ossoff backer who calls himself an “ardent Zionist,” said he detected no softening of support.

“Most of the people in my circle felt like Jon’s actions were appropriate,” he said. “They understand that there’s a role for Jewish senators to play in encouraging Israel to do the right thing.”

Aaron Goldman, a Democratic donor in Atlanta, was once an Ossoff supporter, and was also a significant contributor to Ms. Harris.

He said he was not about to become “somebody who’s going to all of a sudden say it’s OK to be an election denier, or it’s OK to not stand up for the values of reproductive health.”

And Mr. Ossoff, he suggested, should know that the door is open to further conversations with those who feel “quite abandoned.”

But despite his differences with Mr. Kemp, he also signed the letter to him.

“The existential threat of having the world’s only Jewish state be in an unprotected situation,” he said, “is something that is unfortunately more immediate.”

Ruth Igielnik contributed reporting.