Demonstrations against U.S. policy in Israel have spread from the Capitol and college campuses — Cornel West, the left-wing independent presidential candidate, appeared at a rally on Wednesday at the University of California, Los Angeles — to high schools across the country. Students at several high schools in Northern Virginia walked out of classes this week in a “Humanitarian Walkout Week.” The presidents of George Washington and Emory Universities, among others, condemned anti-Israel slogans chanted at rallies and projected on buildings.

An array of liberal groups have adopted the Palestinian cause. This week in New York, one protest sign read, “Reproductive justice means justice for Palestine.” At another demonstration in Manhattan, hundreds marched under the banner of “Queers for Liberation in Palestine.”

“I feel very betrayed by Biden,” said Angela Balya, 28, a protester in Manhattan who said she had volunteered for the Biden campaign in 2020. “I definitely will not be voting for him again.”

The Sunrise Movement, a coalition of young, progressive climate activists that mobilized on behalf of Mr. Biden’s campaign in 2020, is one such group that has called for a cease-fire. Some in the organization have been “raising questions” about whether they and other young people will mobilize for Mr. Biden again, said Michele Weindling, the group’s political director.

“If the Democratic Party and President Biden continue to send weapons and military support to Israel, it threatens to lose our generation, and that’s a very dangerous choice to make ahead of a critical election year,” Ms. Weindling said.

The United States’ support for Israel is unpopular with voters under 35, polling has shown, and students at dozens of colleges on Wednesday afternoon walked out of class as part of a nationwide mobilization effort by the group Students for Justice in Palestine.

“President Biden has shown to people that there’s virtually no difference between Republicans and Democrats on the question of the mass atrocities being leveled against Gaza,” said Kaleem Hawa, who has helped organize student protests with the Palestinian Youth Movement.

Few liberal organizations have had as raw a discussion about Israel as the A.F.L.-C.I.O. did at the Monday night meeting of its executive council.

Mark Dimondstein, the president of the postal union, argued that Israel and the Palestinian territories should be combined into a single state. He called for the A.F.L.-C.I.O. to demand a cease-fire, according to four people familiar with the contents of the meeting.

No other labor leader in the meeting offered vocal support for his position.

Randi Weingarten, the president of the American Federation of Teachers, who is married to a rabbi, responded by asserting Israel’s right to defend itself, the people familiar with the meeting said. Ms. Weingarten said she backed establishing an independent Palestinian state alongside Israel. “That has been part of the Democratic platform for as long as I can remember,” she said.

Mr. Dimondstein, whose union represents more than 220,000 postal workers, said he was “not part of the Democratic Party” and, like Ms. Weingarten, declined to discuss the A.F.L.-C.I.O. call.

“I’m not answering your questions,” he said.

Some of the left-wing demonstrators’ demands fall well outside the American political mainstream.

“The occupation and the existence of Israel is not peaceful; there is no ‘maintaining the peace’ with a violent settler state,” read one bullet in an online document posted by the Democratic Socialists of America and shared widely this week among pro-cease-fire organizers.

At a protest in Manhattan on Wednesday, protesters chanted, “We don’t want no two states, we want all of it.”

Susan C. Beachy contributed research.