Sen. Bernie Sanders (I-Vt.) hosted a lunch on Wednesday for Senate Democrats about the Israel-Hamas war, four people knowledgeable of the gathering said. Shibley Telhami, the Anwar Sadat professor for peace and development at the University of Maryland, spoke to the lawmakers on the issues and confirmed the meeting happened. Three other people said that Telhami was a guest alongside The New York Times’ Tom Friedman and former Middle East peace negotiator Dennis Ross, neither of whom immediately responded to requests for comment.

“Conditions on military aid were raised” by some of the senators, said one of the people.

After POLITICO’s initial reporting, Sanders issued a statement calling for conditioning U.S. aid to Israel, including by ending what he called “indiscriminate bombing” to allow a “significant pause in military operations” so humanitarian aid could enter Gaza; allowing displaced Gazans to return home; no long-term Israeli re-occupation or blockade of Gaza; an end to settler violence and expansion in the West Bank; and a “commitment to broad peace talks for a two-state solution.”

The lawmakers’ talks come as fighting in Gaza intensifies and the civilian death toll rises — an estimated 11,000 dead, according to Hamas-led Gaza health authorities — raising questions among Israel’s traditional allies about red lines for aid.

Democrats’ unequivocal support for Israel’s military has been eroding in recent weeks, going beyond the skepticism progressives have already shown for the administration’s rock-ribbed backing of Israel. If more moderate Democrats join calls for conditioning aid to Israel, it could complicate President Joe Biden’s policy of staunchly standing by the country as it retaliates against Hamas.

In the last week, humanitarian organizations say their offices have been bombarded and staff killed as a result of the clashes. Medical facilities are also under siege and are struggling with a lack of life-saving medical supplies.

Earlier this month, in a call for sending more humanitarian assistance into Gaza, 13 Senate Democrats in a joint statement said “we have been closely monitoring the war in Gaza and believe that much more must be done to protect civilian life … The failure to adequately protect non-combatant civilians risks dramatic escalation of the conflict in the region and imposes severe damage on prospects for peaceful coexistence between Israelis and Palestinians.”

If the hallway conversations turn to legislative action, which would heap immense pressure on the White House, it could force Biden to loosen his hug of Israel as it retaliates against Hamas following the Oct. 7 attack that killed 1,200 people. That would please progressives in Congress who want the United States to demand a cease-fire.

The Pentagon declined to comment. The White House did not immediately respond to requests for comment. Earlier this month, Vice President Kamala Harris said “we are not going to create any conditions on the support that we are giving Israel to defend itself.”

Democrats have not settled on how, or even if, to push for conditions on military aid to Israel. But both lawmakers said current conversations revolve around using existing authorities such as invoking the Leahy Law, which prohibits sending funds to countries where there’s credible information about human rights violations.

Israel receives about $3.8 billion annually from the U.S. for its military and missile defense systems. The Republican-led House earlier this month passed a $14.3 billion aid bill that Biden threatened to veto because it didn’t include funding for Ukraine, among other priorities.

One former senior defense official, also granted anonymity to detail sensitive discussions, said it is “unlikely” the administration will put conditions on its aid to Israel.

“It’s very difficult to condition military aid because how would you guarantee it and how would you construct it? Especially in this instance, we’re not in a position to really instruct a friend and an ally,” the former official said. “Suggest to them, yes. Urge them, yes, but not necessarily condition our aid. I think that would be a bridge too far.”

But the Biden administration has faced mounting pressure over the past week to respond to Israel’s actions — namely its operation at Gaza’s largest hospital, Shifa — as doctors claim their patients, including newborn babies, are at risk of dying.

Some of that pressure is coming from U.S. allies. Alicia Kearns, a conservative British member of parliament and chair of the Foreign Affairs Select Committee, said “it’s absolutely vital that there have to be restrictions” on future military aid to Israel, noting the high rate of civilian casualties when Israel strikes a Hamas target.

Israel has defended its operation at the hospital, claiming Hamas has built tunnels and a command control center underneath. U.S. officials said Washington possesses its own intelligence that supports Israel’s assertion. The operation appears to be ongoing at the hospital, though communications inside Gaza are limited.

The U.S. is in ongoing talks with the Israeli government about potentially establishing safe zones in southern Gaza that would allow humanitarian organizations to operate more freely and away from the crossfire. There are also ongoing talks between Israel and Hamas about a cease-fire, though those conversations appear to have stalled in recent days.

Lara Seligman and Paul McLeary contributed to this report.