Key Democrats are pushing back against progressives who are criticizing the treatment of Palestinians by the Israeli government in the face of what some lawmakers worry could become President Biden’s first foreign policy crisis.

At the furthest end of the spectrum of critics is Rep. Ilhan Omar (D-Minn.), who on Monday called Israeli air strikes that killed civilians in Gaza “an act of terrorism.”

Other progressives, including Sen. Elizabeth Warren (D-Mass.), Sen. Bernie Sanders (I-Vt.) and Rep. Alexandria Ocasio-Cortez (D-N.Y.), have condemned Israel’s plans to evict Palestinian families from the Sheikh Jarrah neighborhood of East Jerusalem, plans that are under review by Israel’s Supreme Court.

Warren called the proposed evictions “abhorrent” and said the Biden administration “should make clear to the Israeli government that these evictions are illegal and must stop immediately.”

Sen. Chris Van Hollen (D-Md.), a member of the Senate Foreign Relations Committee, said “the evictions of families in East Jerusalem would violate international law” and challenged the Biden administration to respond.

“If the Biden Administration puts the rule of law and human rights at the heart of its foreign policy, this is not a moment for tepid statements,” he tweeted.

Israel’s strongest allies in the Senate Democratic Caucus are pushing back against the criticism, arguing that Israel has its own process for determining the legality of the proposed evictions and is absolutely justified in responding with force against rocket attacks from Hamas.

“Israel is a country of law. I have confidence in their judicial system, so let’s let their judicial system play this out,” said Sen. Ben Cardin (Md.), the second-ranking Democrat on the Senate Foreign Relations Committee.

Cardin has called for both Israel and the Palestinian Authority and Hamas not to “take unilateral action” but argued “Israel has to defend itself.”

“It’s an extremely serious situation with Hamas rockets coming into population centers,” he said, adding that he is pleased with the Biden administration’s handling of the situation.

Senate Foreign Relations Committee Chairman Bob Menendez (D-N.J.) questioned the ability of U.S. senators to make sweeping judgments about whether evictions from East Jerusalem are lawful or not.

When asked about Van Hollen’s characterization of the evictions as a violation of international law, Menendez replied with a hint of irony: “I’m glad he’s come to the conclusion.”

But speaking for himself, the senior Democrat said, “I don’t know. I’m not an expert in international law to come to that conclusion.”

“I’m not about to preempt whatever they decide under Israeli laws,” he said.

Sen. Mark Kelly (D-Ariz.), a recently elected centrist, has been following the rising violence closely.

“It’s unacceptable,” he said of Hamas’s rocket attacks. “Israel being our biggest partner in the Middle East and the only true democracy, we’ve got to make sure Israel has what it needs to defend itself.”

Van Hollen said in an interview that he fully supports Israel’s right to defend itself from rocket attacks.

“The Biden administration should weigh in — first of all, as they have — to demand that Hamas stop firing rockets, but the Biden administration also needs to stand up for international law when it comes to issues like evictions, which are a violation of international law,” he said. “Israel has a right to defend itself, but at the same time the administration needs to make sure we stand up for international law.”

Biden says he has spoken with Israeli Prime Minister Benjamin Netanyahu and believes peace can be restored soon. The president has also reached out to Palestinian President Mahmoud Abbas.

A senior Democratic aide said that “it’s a difficult dynamic.”

“Democratic senators, all senators, want to support Israel. But I think there are a lot of Democratic senators — more so on the Democratic side than the Republican side — who believe that Trump shifted the balance too far to the Israeli side at the expense of Palestinians and turned the back on things that the United States has backed Palestinians on,” the aide said.

The Democratic aide said there’s also “some amount of angst” that Biden hasn’t yet nominated his choice to serve as the next U.S. ambassador to Israel.

“It was bound to bite him sooner or later,” the source added.

Sen. Jeff Merkley (D-Ore.), another prominent progressive and a member of the Foreign Relations panel, has raised concerns about Israel’s ability to deploy “disproportionate power,” thanks in part to strong U.S. support.

Raytheon and Israel’s Rafael Advanced Defense Systems have a joint venture to manufacture air defense missiles in Arizona, for example.

Merkley has criticized Hamas as a “terrorist entity” and called the indiscriminate firing of rockets into civilian centers “unforgiveable.”

He says Israel has a right to defend its citizens but also “must reexamine how it deploys its disproportionate power, including its ongoing de facto annexation of Palestinian territory.”

He highlighted “expanding settlements, expropriating land, and locking Palestinians into second-class existence with few rights or opportunities.”

Merkley and other progressives say the Biden administration needs to pressure Israel to adhere more closely to international agreements if there’s to be hope of reviving negotiations toward a two-state solution, a goal they believe slid further away during former President Trump’s four years in office.

Senate Majority Leader Charles Schumer (D-N.Y.), a longtime staunch ally of Israel, earlier this week declined to take a side in the growing debate within his caucus.

“I hope both sides can come together and bring peace,” he said when asked about claims that evicting Palestinians from East Jerusalem would violate international law.

One Democratic senator who requested anonymity said the violence in Israel threatens to spin out of control and become Biden’s first foreign policy crisis.

“Right now, we’re paying for four lost years of American leadership. It used to be that we would try to bridge gaps between the Palestinians and the Israelis. For the last four years we exacerbated the differences. I think we’re perilously close to a Palestinian state being unachievable,” the senator said.

“Part of the work that the Biden administration has to do is draw a harder line with the Israelis on settlements and evictions,” the lawmaker added. “It’s now become a higher priority.

“It might have been a lower priority before missiles were flying back and forth. I don’t think there’s any choice for the administration now” but to focus on the problem, the senator said.