Behind the scenes at the Democratic National Convention, delegates from Uncommitted, a movement calling for a permanent cease-fire in Gaza and an arms embargo on Israel, demanded that a speaker of Palestinian descent address the convention from the main stage, as relatives of a hostage being held in Gaza spoke on Wednesday evening.

The group urged the party in a statement on Wednesday to show balance “by ensuring Palestinian voices are heard on the main stage.” With the convention concluding Thursday, the group added, the absence of Palestinians addressing the gathering “sends a troubling message to our antiwar voters, suggesting they aren’t truly included in this party.”

The statement came after a Jewish magazine, The Forward, reported that the parents of Hersh Goldberg-Polin, who was abducted from Israel on Oct. 7 in the Hamas-led attack that set off the war, would speak at the convention on Wednesday night. “We strongly support that decision and also strongly hope that we will also be hearing from Palestinians,” Uncommitted wrote.

Hours later, Rachel Goldberg and Jon Polin, Chicago natives, took to the convention stage. Wearing pieces of masking tape with the number 320 — the number of days their son has been a hostage — they were greeted with a standing ovation and chants of “Bring them home!” Ms. Goldberg briefly broke down in tears.

“At this moment, 109 treasured human beings are being held hostage by Hamas in Gaza,” she said. “They are Christians, Jews, Muslims, Hindus and Buddhists.”

Ms. Goldberg noted that the hostages were from 23 countries, including eight Americans, one of which is her only son, who like the Democratic nominee, Vice President Kamala Harris, was born in Oakland, Calif. Part of his left arm was blown off by a Hamas grenade on the day he was abducted.

“This is a political convention,” Mr. Polin said. “But needing our only son and all of the cherished hostages home is not a political issue.” He called for a cease-fire, saying, “There is a surplus of agony on all sides of the tragic conflict in the Middle East. In a competition of pain, there are no winners.”

Keith Ellison, attorney general of Minnesota — and in 2006, the first Muslim elected to Congress — also called for a cease-fire in Gaza and for the return of the hostages.

Uncommitted’s campaign to make the war in Gaza a focus of the convention comes as the death toll there has surpassed 40,000, according to Gazan health authorities. Hopes for the survival or recovery of the more than 100 hostages, some believed to be dead, who are still being held in the enclave have grown dimmer. The Israeli military announced on Tuesday that its forces had recovered the bodies of six hostages from a tunnel in Gaza, and the latest effort by the Biden administration to negotiate a cease-fire between Israel and Hamas appeared to have reached a stumbling block, with many issues unresolved.

“The D.N.C. coincides with a critical moment in the negotiations,” Johnathan Dekel-Chen, the father of Sagui Dekel-Chen, a 35-year-old Israeli American hostage, said in an interview. He has been at the convention with the relatives of other American hostages talking to Democratic leaders about the need for a deal, arguing that without an agreement in the coming weeks, there’s a high risk of an escalation of conflicts in the Middle East.

“The moment is critical not just for the hostages but for the region,” he said.

Margaret DeReus, who heads the Middle East Institute for Understanding’s policy project, a nonprofit advocacy group working with Uncommitted, said in a phone interview from Chicago that as she and her colleagues have walked the convention floor — wearing stoles printed to resemble kaffiyehs, the black-and-white scarves that have become a symbol of Palestinians and bearing the words “Democrats for Palestinians” — many attendees have expressed strong support for a permanent cease-fire. But the official convention program has left her feeling “completely alienated,” she said, giving her “a feeling that the party wants to brush the issue of Gaza under the rug.”

Democratic leadership is out of touch with its base when it comes to the war in Gaza, Ms. DeReus argued. But she said she was hopeful that Ms. Harris would “say something that indicates a serious, tangible shift” from the Biden administration’s current policy of staunch support for Israel when she accepts the party’s nomination in a speech Thursday evening.

Rania Batrice, a Democratic strategist of Palestinian descent who was a deputy campaign manager for Senator Bernie Sanders of Vermont when he ran for president in 2016, said Ms. Harris had used “much more humanizing” language when speaking about the plight of the Palestinians, in what she described as a welcome change in rhetoric. The shift is meaningful to Ms. Batrice and her community, she said. “But that won’t stop the bombings in Gaza.”