Moments after he learned his nearly 14 years in Congress were coming to an end, Representative Thomas Massie of Kentucky offered an explanation for his defeat rooted not in his state but thousands of miles east.
“I would have come out sooner, but I had to call my opponent and concede, and it took a while to find Ed Gallrein in Tel Aviv,” he told cheering supporters at his election-night party, referring to the Republican who beat him.
The comment was a clear reference to the millions of dollars spent against Mr. Massie, a longtime critic of Israel and more recently of the war with Iran, by prominent pro-Israel donors and advocacy groups, including a super PAC tied to the American Israel Public Affairs Committee.
The Kentucky race is just one of many across the country in which debates over Israel are raging like never before, dividing not only Democrats but also Republicans as the war in Gaza and Israel’s role in the conflict with Iran have shifted American attitudes toward the Jewish state.
And Mr. Massie’s remark was the latest to strike a nerve among some Jewish leaders, who argue that politicians and their supporters have repeatedly blurred the lines between opposition to Israel and antisemitic tropes about Jewish money and power.
The prominence of such comments in politics — particularly after a series of antisemitic attacks — is alarming and potentially dangerous, they say.
“This is at warp speed, unlike anything I have ever seen,” said Deborah Lipstadt, a Holocaust scholar at Emory University who served as the Biden administration’s special envoy to fight antisemitism. “This is the mainstreaming and normalizing of antisemitism.”
Tensions over Israel have flared up in a House race for a deep-blue district in Philadelphia, where Democrats on Tuesday nominated Chris Rabb, a state representative who made criticism of the country a central part of his campaign.
But, at times, his campaign’s opposition to Israel tipped into promoting falsehoods about Jews.
In December, after the mass shooting at a Hanukkah celebration on Bondi Beach in Australia, Mr. Rabb’s campaign shared an Instagram post saying that the gunmen “were likely Zionists themselves.”
Shortly after the attack, which killed 15 people, Australian authorities said that the gunmen were motivated by “Islamic state ideology.”
In a statement, Mr. Rabb’s campaign said that the staff member who reposted the message had not worked for the campaign for months and that Mr. Rabb had no knowledge of this repost and would never say anything like it.
In Texas, controversy has surrounded Maureen Galindo, a sex therapist and housing activist running for the House as a Democrat — but whose campaign Republicans have quietly helped financially in an attempt to undermine Democrats.
In a lengthy Instagram post, she promised to turn an immigration detention center into a “prison for American Zionists” and claimed that many Zionists were “pedophiles.”
“This bigoted garbage and antisemitism should be nowhere near our politics,” said Representative Alexandria Ocasio-Cortez, the progressive New York Democrat, before she endorsed Johnny Garcia, a Democrat who is facing Ms. Galindo in a runoff election next week.
Representative Hakeem Jeffries of New York, the minority leader, criticized the Republicans who have helped Ms. Galindo because they view her as a weaker opponent in a general election.
“House Republican leadership must immediately cease propping up this antisemitic candidacy,” he said in a statement.
While Israel was not central to the race between Mr. Massie and Mr. Gallrein, it remained a persistent undercurrent.
Across northern Kentucky, many supporters of Mr. Massie said in interviews that his longstanding opposition to any foreign aid to Israel was a key reason they had championed his campaign. At an event for Republicans in Boone County, Ky., last week, one young man wore a T-shirt with the words “Defund AIPAC.”
In the final days of the campaign, an outside group supporting Mr. Massie’s bid released an anti-Gallrein advertisement that showed an image of Paul Singer, a Jewish donor, with a Star of David behind him.
A bizarre incident at a Capitol Hill bar in Washington last week, reported by the news site NOTUS, added to the ugliness. According to the report, William Paul, the son of Senator Rand Paul, Republican of Kentucky, drunkenly told a New York congressman that if Mr. Massie lost, it would be the fault of “you Jews” before starting a tirade about how Jews were “anti-American.” (The younger Mr. Paul apologized and said he was seeking help for a drinking problem.)
The Republican lawmaker he berated, Mike Lawler, is Catholic, and is facing a tough re-election battle in one of the most heavily Jewish congressional districts in the country. (He greeted the news of Mr. Massie’s defeat by writing on X: “My people have spoken. Shalom,” a Hebrew word that can be used to say goodbye.)
Support for Israel has crumbled in both parties, particularly among younger voters.
New polling conducted by New York Times/Siena found that only one-third of Republicans between the ages of 18 and 44 supported providing additional economic and military support to Israel. A majority — 54 percent — said Mr. Trump had been “too supportive of Israel.” Among younger Democrats, 56 percent said their party had been too supportive of Israel.
The issue has spread across primary campaigns, as politicians in both parties try to gain an edge by stressing their opposition to Israel. More than two dozen campaign ads this year have featured messages focusing on Israel, Gaza or Palestinians, according to the media tracking firm AdImpact.
Super PACs affiliated with AIPAC have already spent tens of millions of dollars to support their candidates this year, and are widely expected to spend more in upcoming races in California, New York and Michigan. Some of those efforts have backfired, helping progressives win and underscoring the depth of discontent toward Israel among the Democratic base.
Several progressive candidates have pledged not to take money from the group. And, in the final days of his primary race, Mr. Massie sponsored a bill to require AIPAC to register as a lobbyist for a foreign nation.
AIPAC had rallied against Mr. Massie over his longtime opposition to providing more aid to Israel and his criticism of the country’s conduct in the Middle East. The spending may not have been decisive in his defeat — Mr. Trump’s anger at the congressman dominated the race — but it was an additional challenge for Mr. Massie.
Mr. Massie’s strong criticism of the Jewish state prompted pushback from Jewish leaders, even within his party.
“Massie’s conduct throughout this campaign — trafficking in antisemitism and bottom-of-the-barrel nativism at a time when Jew hatred is on the rise — was wildly unacceptable,” said Matt Brooks, the chief executive of the Republican Jewish Coalition.
A spokesman for Mr. Massie did not immediately respond to a request for comment.
Whether — and when — opposition to the Jewish state tips into antisemitism has become an active debate in both parties.
Republicans are grappling with tensions over free speech, Israel and antisemitism by figures on the far right.
And as the Democratic rank and file grows increasingly hostile to Israel, some Jewish Democrats are struggling with their place in the party.
Last week, a Pennsylvania State Supreme Court justice, David Wecht, announced that he was leaving the Democratic Party, saying “acquiescence to Jew hatred” had become “disturbingly common among activists, leaders and even many elected officials in the Democratic Party.”
Representative Jared Moskowitz of Florida, one of the most outspoken Jewish Democrats in Congress, said in an interview on Wednesday that he had grown increasingly alarmed by public displays of antisemitism.
“We didn’t do enough when this started in our party, and now it has metastasized,” he said. “It is going to be a lot harder to deal with.”
Ruth Igielnik contributed reporting.
