For Congress, the allegations of antisemitism directed towards Representative Ilhan Omar have no precedent. Yet on college campuses, in state legislatures and in many other venues nationwide, the polarised debate about Israel is a familiar conflict and likely to intensify in the months and years ahead.

Fuelled by a wave of youthful activists, including many Jews aligning with Muslims, criticism of Israel’s policies towards the Palestinians has grown in volume and scope, with persistent calls for boycotts and disinvestment. Pro-Israel organisations and politicians have countered with tough responses, and efforts to reconcile the differences have gained little traction.

Among those fearing escalation is Deborah Lipstadt, a history professor at Emory University and author of a new book, Antisemitism: Here and Now, about the recent resurgence of antisemitism in the United States and Europe. She calls herself an optimist, but she says it’s hard to be hopeful in the current political climate.

“Leaders on the left and the right are using this phenomenon as a way of drumming up support, claiming they’re victims,” she said. “I fear it will get far worse before it gets better.”

Congress has never experienced this kind of furore involving a Muslim member accused of anti-Semitism.

Gazans protest as US embassy moves to Jerusalem – in pictures Show all 37 1 /37 Gazans protest as US embassy moves to Jerusalem – in pictures Gazans protest as US embassy moves to Jerusalem – in pictures Palestinian mourners carry the dead body of Mukhtar Ebu Hamas, 25, killed by Israeli forces in Gaza on 14 May Getty Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian woman flashes a victory sign during a protest near the border fence AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures Israeli soldiers guard on top of a watch tower along the Israel-Gaza border AP Gazans protest as US embassy moves to Jerusalem – in pictures Palestinian demonstrators react to fired tear gas Reuters Gazans protest as US embassy moves to Jerusalem – in pictures Palestinian demonstrators run for cover Reuters Gazans protest as US embassy moves to Jerusalem – in pictures US President's daughter Ivanka Trump and her husband Senior White House Advisor Jared Kushner arrive for the controversial inauguration of the US embassy in Jerusalem. The United States moved its embassy in Israel to Jerusalem after months of global outcry, Palestinian anger and exuberant praise from Israelis over President Donald Trump's decision tossing aside decades of precedent. AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures Palestinians carry a demonstrator injured during clashes AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures US Ambassador to Israel David Friedman speaks during the dedication ceremony of the new US embassy in Jerusalem Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian man walks in the smoke billowing from burning tyres AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures Israeli Prime Minister Benjamin Netanyahu waves as he arrives ahead of the dedication ceremony of the new US embassy in Jerusalem. Reuters Gazans protest as US embassy moves to Jerusalem – in pictures Palestinian protesters lying on the floor during clashes Rex Gazans protest as US embassy moves to Jerusalem – in pictures Palestinian protesters burn tires AP Gazans protest as US embassy moves to Jerusalem – in pictures Israel's Prime Minister Benjamin Netanyahu, his wife Sara, Senior White House Advisor Jared Kushner, US President's daughter Ivanka Trump, US Treasury Secretary Steve Mnuchin and US ambassador to Israel David Friedman attend the opening of the US embassy in Jerusalem. AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian man assists a wounded protestor AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian man holding his national flag walks in the smoke billowing from burning tyres AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures US Treasury Secretary Steve Mnuchin and Ivanka Trump unveil an inauguration plaque during the opening of the US embassy in Jerusalem AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures Palestinians carry a protester injured AFP/Getty Gazans protest as US embassy moves to Jerusalem – in pictures Ivanka Trump and US Treasury Secretary Steven Mnuchin stand next to the dedication plaque at the US embassy in Jerusalem Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian demonstrator uses a sling to hurl stones at Israeli troops during a protest against U.S. embassy Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A female Palestinian demonstrator stands amidst smoke Reuters Gazans protest as US embassy moves to Jerusalem – in pictures Ivanka Trump attends the opening ceremony of the new US embassy in Jerusalem AP Gazans protest as US embassy moves to Jerusalem – in pictures Palestinian medics and protesters evacuate a wounded protester AP Gazans protest as US embassy moves to Jerusalem – in pictures An Israeli soldier aims his weapon at Palestinian demonstrators Reuters Gazans protest as US embassy moves to Jerusalem – in pictures Gazans carry an injured protestor Rex Gazans protest as US embassy moves to Jerusalem – in pictures Protestors gather to demonstrate Reuters Gazans protest as US embassy moves to Jerusalem – in pictures An Israeli soldier fires tear gas at demonstrators Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian demonstrator poses with a slingshot Reuters Gazans protest as US embassy moves to Jerusalem – in pictures Protestors carry tires Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A demonstrator kicks a burning tire Reuters Gazans protest as US embassy moves to Jerusalem – in pictures Palestinians congregate prior to their demonstration against the US moving their embassy to Jerusalem Reuters Gazans protest as US embassy moves to Jerusalem – in pictures Female Palestinian demonstrators react to tear gas fired by Israeli troops Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian demonstrator reacts Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian man throws leaflets dropped by the Israeli military during a protest against the US embassy move to Jerusalem and ahead of the 70th anniversary of Nakba, at the Israel-Gaza border, east of Gaza City Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A boy holds a Palestinian flag as he stands amidst smoke Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian demonstrator tries to put out a fire caused by objects dropped from Israeli drones during a protest against the US embassy move to Jerusalem and ahead of the 70th anniversary of Nakba, in Khan Younis in the southern Gaza Strip Reuters Gazans protest as US embassy moves to Jerusalem – in pictures A Palestinian demonstrator with a slingshot REUTERS Gazans protest as US embassy moves to Jerusalem – in pictures Protesters look up at falling tear gas cannisters dropped by an Israeli drone AFP/Getty

Ms Omar, a freshman congresswoman from Minnesota, sparked turmoil within the Democratic caucus with her criticisms of Israel and suggestions that Israel’s supporters wanted lawmakers to pledge “allegiance” to a foreign country. Divided Democrats eventually drafted a resolution that condemned a wide range of bigotry and did not mention Ms Omar by name.

One of the first two Muslim women in Congress, Ms Omar supports a contentious part of the overall dispute — the Boycott, Divestment, Sanctions movement, or BDS, which promotes various forms of boycotts against Israel.

Some celebrities including actress Natalie Portman and singer Lana Del Ray have withdrawn from appearances in Israel in recent months out of concern over Israeli policies. Several scholarly associations, including the American Studies Association and the Association for Asian American Studies, have supported an academic boycott, even as other associations and academic leaders have opposed that campaign.

One of the bitterest cases in academia involved Steven Salaita, whose offer of a tenured faculty position at the University of Illinois was revoked in 2014 after he posted a series of tweets harshly critical of Israel. He sued the university and won a financial settlement, but he was unable to find a permanent academic position elsewhere. He posted a blog piece in February mentioning his current job as a school bus driver near Washington.

In response to the BDS movement, 26 states have passed laws seeking to deter businesses and individuals from participating in it. For example, a Texas law requires contractors who work for or do business with the state to certify they do not boycott Israel or Israeli-occupied territories.

Meet the young musicians of Gaza fighting the siege to play

The American Civil Liberties Union has filed lawsuits challenging the Texas law and similar laws in three other states, saying they violate the right to free speech. A separate lawsuit was filed in Texas by a speech language pathologist, Bahia Amawi, who said she lost her contract with the state because she would not sign the certification.

Among the companies entangled in the conflict is Airbnb, which announced in November it would stop listing properties in the West Bank. Texas officials say the state will halt business with Airbnb because its move ran foul the anti-BDS law. Airbnb says it opposes the BDS campaign and was simply implementing a policy to de-list residences in disputed territories around the world.

One of the groups supporting BDS is Jewish Voice for Peace, which was founded in 1996 and endorsed the boycott campaign in 2015. Rabbi Alissa Wise, the group’s deputy director, says the boycott campaign has been effective, even in the face of state laws seeking to curtail it.

“These laws are meant to silence and repress,” she said. “But they can’t change people’s hearts and minds.”

The Anti-Defamation League, whose mission is to combat antisemitism, denounces Jewish Voice for Peace as “a radical anti-Israel activist group” that advocates a total boycott.

The ADL’s CEO and national director, Jonathan Greenblatt, says not all people engaged in the BDS campaign are anti-Semitic, but he contends the movement itself “is antisemitic in its origins.”

“It is not focused on resolving the conflict in the best interest of all parties,” Mr Greenblatt said.

For now, supporters of Israeli policy have some key advantages: Republicans in Congress are solidly in their camp, as are many Christian evangelicals, who make up a key part of President Donald Trump's political base. But there are some shifts — notably a widening split of viewpoints among Democrats.

Peter Beinart, a journalist, TV commentator and university professor, is one of the prominent American Jews who has been outspoken in criticising Israeli policy. He says his views are shared by an ever-growing portion of younger generations in the US, including Jews.

“You see mobilisation of young millennial Jews in quite a confrontation with their own communal Jewish establishment, which can include their own parents,” he said.

Muqtedar Khan, a professor of political science and international relations at the University of Delaware, shares Beinart’s views about shifting attitudes, but he worries about the response from hardline supporters of Israel.

Meet the girl who wants to be Gaza’s first Olympic Swimmer Show all 10 1 /10 Meet the girl who wants to be Gaza’s first Olympic Swimmer Meet the girl who wants to be Gaza’s first Olympic Swimmer Fatima Abu Shedeg, 13, dreams of leaping from the blocks at Tokyo 2020 Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer Fatima has survived three wars and until four years ago she was not only unable to swim but had never been in a pool Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer In 2014, Fatima lost her father during the last war with Israel, which raged for 51 days and left more than 2,200 Palestinians and 73 Israelis dead. She saw her uncle’s legs blown off in the same airstrike that killed her father and destroyed most of their home in Beit Lahia, north Gaza Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer Like many children in the tiny enclave, she suffered from post-traumatic stress. Then Amjed Tantesh, 42, a swimming coach and one-time Olympic hopeful, encouraged her to learn to swim as a way of channelling her depression and anger Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer “A week after my dad passed away Amjed called my mum and offered me and my brother swimming lessons. My dad was killed by shrapnel from an airstrike which ricocheted off the wall and hit his heart. The same airstrike blew off my uncle’s leg. We were all downstairs screaming,” she said sitting by a small pool filled with murky green water in Gaza City Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer “It’s extremely important for me to achieve my dream, the dream of my family, of my coach, to be the first Gazan swimmer to take part in the Olympics,” she added Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer Four years later, the fitness and football fanatic spends her free time training in grubby and sometimes makeshift pools. Gaza is in the 11th year of an Israeli blockade, meaning Fatima cannot even get hold of proper swimming equipment. She is left to swim in a mismatched pair of pyjamas. If she qualifies it would be her first trip out of Gaza, which is just 25 miles long Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer She said swimming had helped her deal with trauma from the war and made her stronger. “I don’t want to be afraid any more. I want to be strong. I used to even be afraid of the pool, of water, and now I’m not. I’m determined to work on myself, to succeed,” she said Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer Gaza lacks an Olympic-size swimming pool and the few pools it does have struggle to stay open amid chronic energy shortages. It is also increasingly dangerous to swim in the sea Bel Trew/The Independent Meet the girl who wants to be Gaza’s first Olympic Swimmer Fatima hopes one day to get permission to leave Gaza and take her place at the Games. “I want to achieve my dream to be picked for the Olympics, so I can travel and compete in the 100m race,” she said, putting on her swimming pyjamas. “I don’t just want to participate, I want to get first place, so those who picked me are proud.” Bel Trew/The Independent

“For a lot of people who take pro-Palestinian positions, a lot of nasty things are going to happen to them,” he said.

Atiya Aftab, who teaches in the Middle Eastern Studies Program at Rutgers University and chairs Rutgers’ Centre for Islamic Life, has worked for years to promote interfaith dialogue between Muslims and Jews.

She is encouraged by the breadth of support extended to Ms Omar after the congresswoman was criticised, but she worries that bridge-building will become more difficult amid the polarising ideological conflict.

“It’s always lurking in the background,” she said. “The political situation we find ourselves in just creeps in, and I don’t know the solution.”

Both Muslims and Jews have reason to be alarmed by data on hate crimes. The latest FBI report showed a sharp increase in anti-Jewish hate crimes in 2017. FBI data also shows that anti-Muslim attacks have doubled since 2013.

“With antisemitism and Islamophobia on the rise, we have a lot of work to do,” said Aziza Hasan, executive director of a Los Angeles-based Muslim-Jewish partnership called NewGround. “Our destiny is intertwined and we should act like it.”