Over the last few days, several lawmakers have demanded the White House take a tougher stance with its Israeli counterparts. Those lawmakers have called on the administration to push the Israelis to publicly share their plans to ensure civilian safety and address humanitarian issues, such as access to water and fuel, before the United States finalizes additional aid to the country.

“Beyond just a cease-fire, I think it is time for our party to press upon the president to really be a mediating force in what we are seeing in these atrocities in Gaza,” said Rep. Alexandria Ocasio-Cortez (D-N.Y.) in a brief interview. “It is up to the United States to set that standard.”

The demands to make civilian and humanitarian issues a priority are part of a growing chorus of Democrats who have grown more skittish with Israel’s Gaza campaign as it has progressed. They want to see a pause in the fighting to allow civilians to escape Gaza. President Joe Biden on Wednesday said he supported one.

But Israeli Prime Minister Benjamin Netanyahu on Friday forcefully rejected those calls, saying Israel will continue to bombard the Gaza Strip with “all of its power.”

Netanyahu’s refusal to weigh Washington’s request sets Biden up for a stark political clash between a powerful ally and growing progressive pressure over humanitarian concerns.

“I have huge concerns about the current situation,” said Sen. Jeff Merkley (D-Ore.). Along with Sens. Bernie Sanders (I-Vt.), Elizabeth Warren (D-Mass.) and Peter Welch (D-Vt.), he sent the administration a list of questions on the U.S. assessment on civilian deaths, humanitarian needs, how long a war may last and other issues.

“We should push for the values that we uphold, including humanitarian aid and civilians getting out safely and defending civilians against harm during the conflict,” Merkley said.

The clash between the United States and Israel — and the pressure campaign from the left — comes as Congress weighs the Biden administration’s request to send more than $14.3 billion to Israel as part of a nearly $106 billion national security supplemental package. However, lawmakers who have begun openly pressing for a cease-fire or pause in Israel’s Gaza campaign largely believed they missed their opportunity to demand strings be attached to the Israel aid.

The GOP-controlled House voted Thursday to pass a standalone Israel aid package paid for by cuts to IRS funding, making it radioactive to most Democrats. The Senate is putting together a bipartisan proposal that many in the upper chamber hope the House will eventually accept. Lawmakers want to see movement on humanitarian assurances before taking a high-profile vote on the bill, even if they’re not going to demand legislative conditions on the Israel funding.

“The Biden administration has to make certain that the needs of the civilians are being protected. They have a lot of influence over the war plan,” Welch said. “The war plan that Israel has clearly doesn’t take into account the civilian casualties and what’s very worrisome about that is two things — one, civilian deaths, but two, it’s a bad plan. We’ve seen in the past that it just creates more opposition.”

In response to such pressure, administration officials have detailed to lawmakers their “daily” campaign of attempting to hold the Israeli government accountable, and expressing the importance of minimizing civilian casualties and ensuring access to basic needs like water and fuel. And an administration official noted that when the United States transfers weapons to Israel or any other country, it requires that those weapons be used in accordance with the law of armed conflict.

National security adviser Jake Sullivan met with a handful of senators in the White House situation room this week to make that case, according to two attendees who were granted anonymity to speak about the meeting.

“The administration is [pushing] daily — they tell us they’re pushing daily — at every level for a whole series of changes, and I think we’re starting to see some,” Merkley said, recounting recent decisions to turn on water and allow humanitarian trucks to deliver goods.

Other Democratic leaders so far are stopping short of directly calling for a cease-fire. Asked Friday about supporting a cease-fire or a “pause” in the conflict, House Minority Leader Hakeem Jeffries outlined several principles he believed needed to happen — like the defeat of Hamas, the freeing of hostages and the delivery of humanitarian aid — but stressed “how that is managed logistically” was best left to international governments and organizations.

Secretary of State Antony Blinken took the U.S. position on a humanitarian pause directly to Israel on Friday. He told reporters that during a meeting with Netanyahu earlier that day, he urged Israel to pursue a pause in fighting and gave advice about how to minimize Palestinian civilian deaths while targeting Hamas militants in the Gaza Strip.

Shortly after, Netanyahu said Israel “refuses a temporary cease-fire that doesn’t include a return of our hostages.”

Some progressives have called for conditions on Israel aid in the past, most notably, Warren in 2021. But the idea of doing so now, in the wake of the Oct. 7 Hamas attacks that killed 1,400 Israelis, has gained little ground beyond some of the most progressive lawmakers and stands little chance of passing in either chamber of Congress.

Any kinds of conditions placed on the aid would lose votes from the moderate pro-Israel wing of the Democratic caucus. Rep. Brad Schneider (D-Ill.), for example, voted against the House GOP-led bill Thursday, in part because of the conditions placed upon the aid.

Some Democrats unsuccessfully lobbied the White House shortly before the national security defense supplemental was released in hopes of getting restrictions or additional humanitarian aid added to the original request, said Rep. Mark Pocan (D-Wis.).

Now that the funding request is already out, “most of the groups and many members of Congress kind of missed our best chance,” he said, though he added Rep. Barbara Lee’s (D-Calif.) efforts helped increase the amount of humanitarian aid in the initial ask by roughly a billion dollars.

Democrats now find themselves caught between staunchly supporting a U.S. ally with the prospect of perpetuating a bloody military campaign that has faced criticism on moral grounds.

“While I support Israel and Israeli democracy, I have real hesitation in what I’m seeing,” said Rep. Mark DeSaulnier (D-Calif.). “And this [idea of] trust the Israeli government, that they’re being strategic and trying to be careful — Why would I do that? That’s not my job to just trust.”