An Israeli prime minister who has embraced Donald Trump and taken rightwing populism from his playbook. And a group of fiery young Democrats unafraid to question their elders or challenge the status quo. Put together, the elements were bound to be explosive.

Democrats were expected to offer a resolution condemning antisemitism on the floor of the US House of Representatives on Thursday following the latest provocative comments by Ilhan Omar of Minnesota, who in January became one of the first two Muslim women in Congress.

But the vote was pushed back as Democrats became increasingly divided over the language of the resolution, and whether it would be broadened to include anti-Muslim bias – a sign of the delicate balancing act for Democrats on a notoriously complex issue spanning identity politics, party politics, geopolitics and a generational divide.

On Wednesday, Democrats accused Speaker Nancy Pelosi and other leaders of trying to rush out the resolution after Omar last week suggested the Jewish state’s supporters are pushing lawmakers to pledge “allegiance” to a foreign country.

“As a member of Congress I should not get important information from cable news,” Democratic congresswoman Jahana Hayes of Connecticut, who also took up her seat in January, said in a statement.

Meanwhile, the controversy spread to the White House and the Senate.

“It is shameful that House Democrats won’t take a stronger stand against Anti-Semitism in their conference,” tweeted President Donald Trump, who has himself been accused of stoking anti-semitism. “Anti-Semitism has fueled atrocities throughout history and it’s inconceivable they will not act to condemn it!”

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Vermont Senator Bernie Sanders, who is running for president as a Democrat in 2020 and is Jewish, defended Omar.

“Anti-Semitism is a hateful and dangerous ideology which must be vigorously opposed in the United States and around the world. We must not, however, equate anti-Semitism with legitimate criticism of the right-wing, Netanyahu government in Israel,” he said.

“What I fear is going on in the House now is an effort to target Congresswoman Omar as a way of stifling that debate,” he continued. “That’s wrong.”

Democrats and Republicans alike have long expressed a rock-solid alliance with Israel. Leaders of both parties frequently address the annual American Israel Public Affairs Committee (Aipac) conference in Washington, which is coming up later this month.

Omar and other critics suggest that Aipac has too much sway over US policy. At last year’s conference the Israeli prime minister, Benjamin Netanyahu, delivered a bellicose speech and “saluted” Trump for his plan to withdraw from the Iran nuclear deal.

Democratic party elites silence Ilhan Omar at their peril | Trita Parsi and Stephen Wertheim Read more

Indeed, Netanyahu and Trump have perhaps the closest relationship of any two Israeli and US leaders in history, and much in common. Israel’s attorney general has said he intends to indict Netanyahu on corruption charges, while Trump is under investigation by the justice department, House Democrats and the federal prosecutors of the southern district of New York. Both men have punched back aggressively and cried “fake news!” Both are also accused of siding with far-right extremists in ways that threaten their respective democracies.

So while there is nothing new about the US-Israel relationship drawing scrutiny from the left, the political moment is ripe. And it coincides with a younger generation far more willing to challenge old orthodoxies of foreign policy. In Congress, they are personified by Democratic newcomers including Omar, Alexandria Ocasio-Cortez, Pressley and Rashida Tlaib, who is also Muslim.

“Being opposed to Netanyahu and the occupation is not the same as being antisemitic,” Omar, a hijab-wearing Somali American, tweeted on Sunday. “I am grateful to the many Jewish allies who have spoken out and said the same.”

Omar has apologised for a 2012 tweet in which she said Israel had “hypnotised” America, then again for suggesting that members of Congress support Israel because they are paid to do so. Both remarks were condemned for employing antisemitic tropes, including by some who do not shy away from criticising Israel when the occasion demands.

Then came a third incident. Speaking at a progressives’ town hall event in Washington last week, Omar said: “I want to talk about the political influence in this country that says it is OK for people to push for allegiance to a foreign country.” Again, there was bipartisan outrage. Democrat Eliot Engel, chairman of the House foreign affairs committee, said it was a “vile antisemitic slur”. This time Omar refuses to say sorry.

Kerri Evelyn Harris, a progressive former 2018 Democratic candidate for the US Senate in Delaware, was in the audience as Omar spoke. “She was very emotional when asked that question and her voice broke holding back the tears,” Harris said via text message. “The media is pulling out pieces of her comment in what I consider to be an attempt to divide people.”

She added: “It’s a high-ratings controversy and the party and the movement alike are allowing it to drive a wedge out of reaction.”

Facebook Twitter Pinterest Post-it notes of support are left outside the office of Representative Ilhan Omar. Photograph: Andrew Harnik/AP

Some on the left regard the fierce backlash as an alliance between Republicans and centrist Democrats, and speak of the foreign policy establishment lashing out by using charges of antisemitism. They suggest that there is a concerted effort to “nuke” Omar now as a warning to others in her generation against speaking out.

The Democratic congressman Juan Vargas of California tweeted that Omar was perpetuating “hurtful anti-Semitic stereotypes” and added that “questioning support for the US-Israel relationship is unacceptable”. Ocasio-Cortez shot back: “Plenty of Dem members have asserted that discussion + debate on this issue is fair and merited. Is this stance a departure from that?”

Plenty of Jewish Americans do debate the US-Israel relationship. Jill Jacobs, executive director of T’ruah: The Rabbinic Call for Human Rights, said: “Israel is a country and a member of the UN, subject to the same international conventions and treaties. But it is unfortunately not uncommon for criticism of Israel to cross a line into antisemitism, which is what happens when you have tropes about money or an international conspiracy.

“Congresswoman Omar used a couple of stereotypes, but we are hyper-focused on her remarks and some are weaponising those remarks in a way that will hurt the Jewish community.”

Facebook Twitter Pinterest White nationalist groups marched in Charlottesville, Virginia, in 2017, many chanting ‘Jews will not replace us!’ Donald Trump said they included some ‘very fine people’. Photograph: Mykal McEldowney/AP

Some observers detect hypocrisy, suggesting that Omar is being singled out disproportionately because she is a Muslim woman and Democrat. After white supremacists marched in Charlottesville, Virginia, chanting “Jews will not replace us!” in 2017, Trump insisted “there were very fine people on both sides”.

Charles Chamberlain, chair of Democracy for America, a progressive political action committee, said that while Democrats oppose antisemitism, “everyone paying attention knows that the particular resolution is being pushed right now, not to hold Republicans accountable for the countless times they have stood silently as the president whitewashed neo-Nazis, but instead to tell a newly elected, black, Muslim, refugee Congresswoman to sit down and shut up”.

Ilhan Omar should be more radical about Israel, not less | Barnaby Raine Read more

Democratic congressional leaders, he added, are playing “directly into the hands of rightwing forces in the United States and abroad, looking to divide Democrats and ignore essential questions about American foreign policy”.

Omar has faced ferocious blowback. An anti-Muslim poster outside the chamber of the West Virginia house of delegates falsely connected her to the 11 September 2001 terrorist attacks. Haroon Moghul, a fellow in Jewish-Muslim relations at the Shalom Hartman Institute of North America, said: “It’s not only a double standard on antisemitism but I’m yet to hear Republicans propose a resolution to condemn Islamophobia. Why speak out against one form of bigotry and not another?”

But Moghul also said he wanted more from Omar. “My general disappointment is that rather than telling us what she’s for, she’s telling us what she’s against.”