Israel's war in Gaza became a political flashpoint. Will it risk Biden's coalition for reelection?

Presidential election cycles of years past are riddled with examples of major foreign policy issues that shook the international order, dominated headlines and even debates -- but ultimately were not top of mind for American voters.

Experts and analysts wonder if that will change with the 2024 race because of one issue: the Israel-Hamas war, sparked by Hamas' Oct. 7 terror attack, and the ensuing humanitarian crisis in Gaza, which have increasingly loomed over parts of the Democratic base.

Interviews with more than a dozen activists, Democratic operatives and voters revealed uncertainty over whether the six-month-old war in Gaza, already the longest in Israel's history, is significantly shifting political allegiances in the U.S. by turning away voters who would otherwise back President Joe Biden -- or if the detractors are split between voters who will either come home to the president in November or would have found some reason not to support him regardless.

"Potentially," Wa'el Alzayat, the head of Muslim advocacy organization Emgage, said when asked if Gaza is different in its electoral fallout.

"I think this is a rare occurrence in American politics, but we have clearly seen that this policy is unpopular in the Democratic Party," he added.

Biden only narrowly defeated rival Donald Trump in 2020, despite winning the popular vote by nearly 5 points -- and their rematch is expected to be similarly close, likely coming down to thin margins in a handful of states in which any movement among voting groups could be decisive.

"The president won his ticket by cobbling together a coalition of different groups under the big Democratic tent, as they say, and his policy is at odds with his electoral strategy because it's fracturing the party," Alzayat said. "And it's not just Arabs or Muslims. You're seeing progressives, young voters, Black voters, liberal Jewish voters or progressive Jewish voters. This is a pretty good segment of the party."

Left-leaning groups and anti-war activists have been voicing their fury or frustration with Biden over his ongoing support for Israel's campaign against Hamas, which has come with a high death toll, largely in Gaza.

Protesters have disrupted some of Biden's events and tens of thousands of Democratic primary voters have been encouraged to signal displeasure by backing other ballot options in several states' primaries, including key battlegrounds like Michigan.

Biden has acknowledged those concerns and sought to balance his backing for the fight against Hamas with sympathy for the Palestinians, while criticizing some Israeli operations as excessive. He has also amped up pressure on Israel to allow more humanitarian aid to enter Gaza – in particular, after the death of seven aid workers with the World Central Kitchen last week in an Israeli strike.

In the wake of that strike, which Israeli officials called a "terrible" mistake, Biden spoke with Israeli Prime Minister Benjamin Netanyahu for about 30 minutes and "made clear the need for Israel to announce and implement a series of specific, concrete, and measurable steps to address civilian harm, humanitarian suffering, and the safety of aid workers," the White House said.

In a statement for this story, Biden campaign spokesperson Lauren Hitt reiterated past comments that he "shares the goal for an end to the violence and a just, lasting peace in the Middle East" and is "working tirelessly to that end."

But the persistent backlash has raised the specter among advocates and political experts that the war in Gaza could do what other major foreign policy issues have not in past elections: sway an important number of voters at a time when the U.S. is not itself at war.

Since the end of the Cold War, domestic issues -- chiefly the economy -- have reigned supreme in presidential elections, experts said, with foreign imbroglios rarely notching a spot in polls as a top issue.

More recent surveys show that's still the case, with exit polling from the 2016 and 2020 presidential elections showing voters more concerned about issues like the economy and COVID-19.

Gallup has long tracked what Americans feel is the country's "most important problem," and the economy dominated the public's concerns in the six years after the start of the Great Recession before dropping to a single-digit low in January 2021 -- the height of the pandemic -- and then rising steadily since.

In the last seven months, from September to March, Gallup polling found that mostly domestic issues led the list of the country's "most important" problems: the economy, immigration, leadership, cost of living, and poverty and homelessness.

Experts pointed to one major exception to this trend in recent decades, in 2004, when the Iraq War was fresh and debate raged over whether the fight was worth the sacrifice. Exit polls showed at the time that Iraq was one of the four most important issues to voters, not far behind the economy.

Why would the Israel-Hamas war make a difference in voter opinion?

Israel and the U.S. have long been close allies, with numerous social and cultural ties between them, and some Americans have been among the casualties and the hostages thought to be taken by Hamas after the October attack.

Activists pointed also to the lengthy history and existing familiarity, among many Americans, with the Israeli-Palestinian conflict to suggest that voters find it more accessible than other international turmoil. That has led to a more visceral response about the involvement of the U.S. in a way the civil war in Yemen or the reported abuses of the Uyghur minority in China, for example -- both of which are large-scale conflicts or controversies -- have not.

Even the ongoing Russian invasion of Ukraine, which has involved billions in U.S. aid, significant attention from U.S. leaders and an enormous death toll of its own, is not appearing in polling as a top issue in the 2024 election.

"The horrors of Gaza are exceptionally bad in comparison to any conflict we've seen in recent memories, including Yemen. And it's also the intensity and the carnage in such a short span of time," said Alzayat.

Demographics play another role, observers say: There are notable Jewish, Muslim and Arab communities in different parts of the U.S. who have helped drive domestic attention on the conflict.

Polling indicates there has been a shift in recent years in American sympathies for the Israelis or the Palestinians, with the change being more pronounced among Democrats, according to Gallup tracking that showed rising sympathy for the Palestinians going from 19% to 27% in early 2024 while sympathy for the Israelis has dropped in that same period from 64 to 51%.

More Democrats are sympathetic toward the Palestinians than the Israelis, Gallup found, while more independents and Republicans are sympathetic toward the Israelis.

Operatives suggested the changing reaction to the war in Gaza is influenced in some left-leaning circles by broader conversations in the U.S. about social justice and the treatment of communities of color, which can squeeze complicated dynamics into a simpler "narrative," as one source put it.

"I think this fits very neatly into the social justice framework of the Palestinians being an oppressed group," said a person directly familiar with the Biden team's strategy, who was not authorized to speak to the press and asked not to be quoted by name to be more candid.

On top of that, extensive social media content about the war -- including photos and videos from inside Gaza -- has brought the conflict between Israel and Hamas to people's phones in a way that other conflicts couldn't.

More than more than 33,000 people have been killed and about 76,000 others injured in the Palestinian territory, according to the Hamas-run Gaza Ministry of Health.

In Israel, at least 1,700 people have been killed and 8,700 others injured, according to the Israeli Ministry of Foreign Affairs.

"The other factor I think people underestimate is the role social media plays in how people are getting their information and news now. And you could ask yourself -- would the Iraq War have played out differently if there was TikTok or Instagram back in the early 2000s? And that's the question I ask people, but I think most definitely, we can say yes," said Abed Ayoub, the national executive director of the American-Arab Anti-Discrimination Committee, which supports a cease-fire.

Popular opinion about Israel's response has begun to fade: According to a Gallup survey conducted in March, approval among Americans of Israeli military action in Gaza dropped from 50% to 36%.

Trump, for his part, has suggested Biden's failures as a leader are to blame for crises elsewhere, including in Israel and in Ukraine.

The source familiar with Biden's campaign said they believe that "Gaza is different than your typical foreign policy issue" and could be particularly damaging at a time when Biden is in a tight battle in early polling against Trump and "has lost ground with young voters."

"The war in Gaza, while not the biggest factor in that, is certainly a contributing factor, I think, in that loss, and, perhaps more importantly, an obstacle to him making the inroads that he needs among those young voters," this person said.

Voters said as much when asked by ABC News if the war is an impediment to their support for the president.

'No longer proud'

"There's nothing that will get me to vote for Joe Biden in November," said Heba Mohammad, the former digital organizing director of Biden's 2020 Wisconsin campaign. "I'm no longer proud to have worked for him to get him elected."

Others, though, were more skeptical that the criticism would make too much of a dent in Biden's support in the general election.

Where some saw a fracturing in Biden's coalition, other Democratic operatives instead suggested that many of his critics are merely voicing their frustrations while planning to vote for him when it's a binary choice with former President Trump -- and that those who walk away would have done so regardless.

"What we're seeing is voters saying, 'I'm angry at President Biden on this issue, and I disagree,' but recognizing that Trump is a greater threat to a number of other issues that people care about," said Democratic strategist Karen Finney.

A Democratic pollster with presidential campaign experience, and who said they couldn't be quoted by name because of professional concerns, also voiced skepticism about the ultimate amount of anti-war voters who could only be won over to Biden with a cease-fire pledge.

"He's taken a public pivot," this pollster said. "He's called out Netanyahu, people in his administration have called out Netanyahu."

Biden's "official position is calling for a cease-fire now," the pollster said, referring to the White House's stated goal of at least a six-week pause in the fighting to allow for more aid in Gaza and the release of Hamas' hostages. "How can anyone legitimately in good faith say that they're not voting for him because of this? That's why I don't believe it's a real thing."

Even some Biden critics appear ready to pull the lever for the president when the war is judged in the context of a rematch with Trump, instead viewing their vote for ballot alternatives as a wake-up call.

"The vote for now is really to send a message. I don't really know what's going to happen in November. I'm hoping to support Biden," said Rima Mohammad, a Palestinian American living in Ann Arbor, Michigan, where more than 100,000 people picked an "uncommitted" delegate over Biden in the state's Democratic primary -- though that number is still dwarfed by Biden's overall number of votes in the primary, across the country.

"Anything to beat Trump, but we need to get Biden's attention and I think by voting on uninstructed or uncommitted like the other states are he will realize that a lot of his base support is displeased," added Sally Morgan, a voter in Milwaukee who likewise said she'll back the president in November.

In the end, some activists said that while it's difficult to put a true number on how many voters are lost to Biden and how many will come back, Election Day will likely show a mix.

"I think some people will sit it out, because just the moral revulsion of what's happening abroad," said Joseph Geevarghese, the executive director of progressive group Our Revolution. "That being said, I do think that some segment of the uncommitted vote will obviously say, 'Well, Biden is better than Trump, bigger picture.'"

Yet just as the war is not happening in a vacuum, public opinion on it isn't static, either -- and Democrats warned that as the fighting drags on, the number of voters turning their backs for good could grow.

James Zogby, a Democratic National Committee member and founder of the Arab American Institute, said he believes "a lot of people are going to take the position that" Biden "has brought all hell down on Gaza. And what's the difference here?"

"That will be a mindset that I hear, and that mindset could have been changed," Zogby said. "I would hope that it still can be changed. But I'm losing confidence that it will be."

ABC News' Mary Kekatos, Molly Nagle and Zohreen Shah contributed to this report.