Seven months into Israel’s war in Gaza, Muslim and Arab American leaders say their channels of communication with President Biden’s White House have largely broken down, leaving the administration without a politically valuable chorus of support for his significant shift on the conflict this week.

Mr. Biden’s announcement that he had paused a shipment of 3,500 bombs to Israel and would not help with a ground invasion of Rafah was a sea change in U.S. policy that Arab American and Muslim leaders have demanded for months. But those who desired it the most have long ago written off the administration as complicit in a war that Gaza officials say has killed more than 34,000 people, arguing it was, essentially, too little, too late.

“The president’s announcement is extremely overdue and horribly insufficient,” said Abbas Alawieh, one of the leaders of a protest-vote movement against Mr. Biden that began in Michigan this year. “He needs to come out against this war. Period. That would be significant.”

Mr. Biden’s White House aides engaged in considerable outreach at the outset of the Democratic primary season, when the movement to cast protest votes in early states emerged as a surprising political headache. A cadre of high-level aides traveled to Dearborn, Mich., and Chicago to demonstrate their interest in listening, but Arab American leaders told them that without a momentous shift in U.S. policy — such as support for a permanent cease-fire — there was no need to keep talking.

By and large, prominent Muslim and Arab Americans have now concluded that they are irrevocably at odds with the Biden administration over its foreign policy, according to interviews with more than a dozen people involved in the talks. And many of them say they are tired of hearing that they should vote for Mr. Biden simply because former President Donald J. Trump would be worse.

“I have told them frankly: ‘Don’t waste your time anymore unless you have something substantial. This is a waste of time,’” Osama Siblani, the publisher of The Arab American News, an influential newspaper in Dearborn, said of White House officials.

The inability to maintain useful lines of communication with groups that represent a vocal, if small, bloc of Democratic voters could pose a significant problem for Mr. Biden’s re-election, given that the contest is likely to be determined by narrow margins in a few battleground states. The protest effort against Mr. Biden garnered double-digit support in some states during the Democratic primaries, although Biden aides believe that voters will ultimately see Mr. Trump as the bigger threat, and that issues like abortion, democracy and the economy will take precedence over Gaza.

Mr. Biden has ensured that the White House, rather than his re-election campaign, handles outreach to Arab and Muslim communities angry about the war in Gaza, since their dispute centers on policy rather than electoral politics. While the White House has designated an official, Mazen Basrawi, as its “liaison to American Muslim communities,” no one on Mr. Biden’s re-election campaign has a similar responsibility. Mr. Biden’s campaign aides say they are leaving such outreach to the White House for now at the request of community leaders.

Mr. Basrawi was among the officials in the White House delegations to meet with Arab American and Muslim leaders this year in Dearborn and Chicago. The February meeting in Dearborn took place only after the city’s mayor made a public show of refusing to meet with Julie Chavez Rodriguez, the campaign’s manager.

At the Dearborn meeting, in which a senior White House foreign policy aide expressed regret for the administration’s response to the war in Gaza, Mr. Basrawi apologized for a lack of engagement from the Biden administration with Dearborn officials.

“Just so you all know, we have been engaging with both the Arab community, particularly the Palestinian community and the Muslim community broadly, on a lot of these issues since October,” Mr. Basrawi told the group, according to an audio recording of the meeting reviewed by The New York Times. “To the extent that I’ve neglected to include all of you in my engagement, that’s on me. You know, this is an important community nationally.”

In an interview on Thursday, Mr. Basrawi said he was speaking to more officials now than he did before the war in Gaza began.

“My circle of contacts and regular conversations with leaders in the Muslim and Arab communities has grown since Oct. 7 to include more leaders on the local level,” he said.

The White House continues to reach out to Muslim and Arab American groups who remain willing to engage, particularly elected Democratic officials. White House officials met with a group of Lebanese Americans last month in Houston. And the White House’s Office of Public Engagement maintains an email list updating Muslim American leaders on the administration’s work on Israel and Gaza.

“We recognize that this is a painful time for many communities and that people have strong personal views,” said Andrew Bates, a spokesman for the White House. “It’s why the president remains deeply engaged in securing a hostage deal that would result in an immediate and sustained cease-fire.”

Secretary of State Antony J. Blinken is planning to meet with several prominent Arab American groups, according to three people familiar with the meeting who insisted on anonymity to discuss the private planning. But the event has been delayed, at a time when Mr. Blinken’s heavy travel schedule has repeatedly taken him out of the country.

There are limits to the people and groups that Mr. Biden’s White House will engage with about the Gaza conflict. The administration disavowed and cut off communication with the Council on American-Islamic Relations in December after its executive director said that Palestinians in Gaza had “the right to self-defense” but that Israel “as an occupying power” did not. (The group has said the comments were taken out of context.)

A White House official, who was granted anonymity to discuss internal strategy, said the administration would engage with people critical of Mr. Biden’s handling of the conflict but had cut ties with those who praised the Hamas attack on Oct. 7, made antisemitic statements or questioned Israel’s right to exist.

As the pro-Palestinian movement has spread beyond Arab American and Muslim communities to young people and progressives, those with direct or ancestral ties to the region have tended to carry the most influence in criticizing Mr. Biden and the White House’s outreach effort.

Wa’el Alzayat, the chief executive of Emgage, a group with close ties to the Biden administration that mobilizes Muslim voters, turned down an invitation to attend an iftar dinner at the White House last month.

“We don’t take lightly the opportunity to meet with the president,” Mr. Alzayat said. “But at some point, as organizations that have turned out the vote largely for Democrats, by expecting us to show up to these things and not delivering on policy, they’re actually burning us.”

He called Mr. Biden’s threat to cut off arms shipments “promising and important” and a result of pressure from antiwar leaders, but he said it “might be too late for Rafah,” as Israeli tanks and warplanes continue to bombard the city.

Some Arab Americans who have long had an entree to high-level Democratic politics expressed feelings of deep alienation.

“I’ve never had the feeling of being so shut out as I feel right now,” said James Zogby, a founder of the Arab American Institute in Washington and a Democratic National Committee member since 1993. “And it’s not just me. It’s leadership across the country.”

Mr. Zogby’s most recent letter to the White House, he said, has gone unanswered for three months, alongside numerous text messages and phone calls.

If some voters do break with Mr. Biden over Gaza, they are more likely to stay home or opt for a third party than vote for Mr. Trump. The former president has a long history of using anti-Muslim language, and he banned travel from several predominantly Muslim countries while in office. On Thursday, he voiced support for the invasion of Rafah, saying that Israel had to “get the job done.”

Democratic officials who are sympathetic to the Palestinian cause and who have engaged in talks with the White House are very careful about how they characterize those discussions publicly, given the anger among Muslim and Arab American voters.

Two mayors with whom White House officials said they had spoken about the Gaza conflict, Abdullah Hammoud of Dearborn and André Sayegh of Paterson, N.J., both declined to be interviewed.

Among Democrats who support Israel’s continued offensive in Gaza, Mr. Biden’s threat to halt arms was met with anger and concern. Politically, some worry that Mr. Biden may lose support from Jewish Americans and moderates. Mark Mellman, the founder of Democratic Majority for Israel, said in a statement that it was “dangerous” to weaken the U.S.-Israeli alliance.

Although polling has shown that Gaza is not a top issue for most voters, including young people, some Democrats supporting Mr. Biden fear that his Israel policy has alienated activists who could help his campaign on the ground.

“The people who are going to knock on doors and do social media and build the rallies, a lot of them do care deeply about the war,” said Representative Ro Khanna of California, a surrogate for the Biden campaign. “It’s more than just the polling. It’s how are we going to get our core group of organizers and activists inspired to be fully out there come the fall?”

Michael Gold contributed reporting.