WASHINGTON — U.S. Senate leaders called Tuesday for a bipartisan aid package for Israel’s counteroffensive against Hamas that also includes assistance for Ukraine and Taiwan, with possible border funding sought by Republicans, as President Joe Biden prepared to leave Tuesday evening for a trip to Israel.

Meanwhile, an explosion killed hundreds Tuesday at al-Ahli Arab Hospital, also known as Baptist Hospital, in Gaza City, according to Palestinian officials who blamed the blast on Israeli forces.

Israel denied responsibility, saying enemy rockets “passed through the vicinity of the hospital when it was hit,” the office of Israel’s Prime Minister Benjamin Netanyahu posted on X.

In Washington, the Biden administration is preparing a supplemental budget request, which senators expect to see by the end of the week, Senate Majority Leader Chuck Schumer told reporters Tuesday.

The package will include funding for Israel to address military, intelligence and humanitarian needs as the U.S. ally retaliates against Hamas for the militant group’s attack on Oct. 7, Schumer, a New York Democrat, said.

The package will also include aid for Ukraine and Taiwan, Senate Majority Leader Mitch McConnell said.

But the Kentucky Republican added Republicans would also seek to add funding for security measures at the U.S.-Mexico border.

“We’d like to get the supplemental package moved as quickly as possible because the needs are great in both Israel and Ukraine,” Schumer said.

Schumer, who led a bipartisan delegation of senators to Israel over the weekend, said the package would have “the military help Israel needs, the diplomatic and intelligence help Israel needs, as well as humanitarian aid to minimize the loss of innocent human life of Palestinians and of Israelis.”

Senate Republican Whip John Thune of South Dakota said at a Tuesday press conference the caucus was “heartbroken and disgusted” by Hamas’ surprise attack that killed more than 1,300 Israelis, most of them civilians. Senate Republicans stood “in solidarity with Israel,”, and supported the country’s right to exist and to “defend itself” from the Hamas attack, he said.

But Republicans also sought additional funding for border security, criticizing Biden for not prioritizing the issue.

“The administration will send up a supplemental that deals with Israel, Ukraine, Taiwan,” McConnell said. “And Republicans are going to want something serious about the border. And so we’ll take a look at the package when they send it up, make suggestions to improve it if that’s needed, but clearly the world has changed dramatically in the last 10 days.”

Biden heads to region

Biden was scheduled to depart Tuesday evening for Israel.

Biden will “talk about how important it is for the United States and other partners to stand up for Israel and allow them to continue to defend themselves against Hamas terrorists,” White House Security Council spokesman John Kirby said in a video on X.

“The United States support will stay strong and steady,” he said.

The president will warn others in the region who may seek to widen or deepen the conflict to stay out, Kirby said.

U.S. Secretary of Defense Lloyd Austin issued a “prepare to deploy order” to 2,000 Defense Department personnel Monday, Pentagon spokesperson Sabrina Singh said at a press briefing.

“This directive increases DOD’s ability to respond quickly to the evolving security environment in the Middle East,” Singh said.

Biden will also work with Israel to secure hostages, including U.S. citizens, being held by Hamas and will speak to the humanitarian situation in Gaza, Kirby said. The administration wants to see food, water and medicine flow into Gaza and that there is safe passage for civilians to get out, he said.

Biden was previously scheduled to meet with Jordanian King Abdullah, Egyptian President Abdel Fattah el-Sisi and Palestinian Authority President Mahmoud Abbas in Amman after departing Israel, but the White House announced late Tuesday that the president will postpone the visit after Abbas announced days of mourning.

“The President sent his deepest condolences for the innocent lives lost in the hospital explosion in Gaza, and wished a speedy recovery to the wounded,” the White House said in a statement. “He looks forward to consulting in person with these leaders soon, and agreed to remain regularly and directly engaged with each of them over the coming days.”

Secretary of State Antony Blinken has been in the region this week negotiating a safe passage for evacuees from Gaza to Egypt via Rafah and allowing humanitarian supplies to enter Gaza by the same crossing.

Former Senate Foreign Affairs Chairman Bob Menendez, a New Jersey Democrat, will not participate in a classified briefing on the Israel-Hamas war, Schumer said.

Menendez stepped down from his committee role after he was accused in a federal criminal indictment of being an unregistered agent of the Egyptian government, as well as bribery charges.

Egypt is the only country other than Israel that shares a border with Gaza.

Hospital explosion

The Pentagon could not confirm who caused the explosion at al-Ahli Arab Hospital or the number of casualties, Singh told reporters.

“I’ve seen the reports, I don’t have any more details to provide at this time,” Singh said during a televised press conference. “I don’t know who is responsible. We don’t have all the facts. And I’m sure as we learn more that will inform conversations, but right now I’m not going to go down a hypothetical road of who is responsible for something.”

“What I can tell you again is that what the secretary (Austin) has been very clear on is that we expect Israel to uphold the law of war,” Singh said.

Palestinian Authority Prime Minister Mohammed Shtayyeh called the shelling a “massacre” and “horrific crime.”

Netanyahu’s office posted on X: “According to intelligence information, from several sources we have, the Islamic Jihad terrorist organization is responsible for the failed shooting that hit the hospital.”

The World Health Organization immediately condemned the “apparent attack” on the operational hospital, one of many under an evacuation order from the Israeli military.

“We call for the immediate protection of civilians and healthcare, and for the evacuation orders to be reversed,” WHO chief Tedros Adhanom Ghebreyesus posted on X.

The United Nations has expressed concern over Israel cutting supplies to the Gaza Strip.

“Crucial life-saving supplies – including fuel, food and water – must be allowed into Gaza.? We need rapid and unimpeded humanitarian access now,” UN Chief António Guterres said in a statement.

Israel has reopened access to water in the southern Gaza, Singh said Tuesday. Israel ordered an evacuation from the north part of the territory, affecting more than 1 million civilians, last week.

The administration will continue to remind Israel not to target civilians and follow other international laws of war, but would not put conditions on U.S. aid, Singh said.

‘We need a confirmed ambassador’

The Senate Foreign Relations Committee is scheduled to hold a confirmation hearing Wednesday for Jack Lew to be the U.S. ambassador to Israel.

Maryland Democrat Ben Cardin, who chairs that committee, said Tuesday the Senate should confirm Lew promptly.

“We need a confirmed ambassador in Israel as soon as possible,” he said. “We’ll work to make sure that’s a reality as soon as possible.”

McConnell was noncommittal when asked if Republicans would support Lew, a former Treasury secretary under Democratic President Barack Obama.

“We’ll take a look at it,” McConnell said of Lew’s nomination.