President Joe Biden spoke with Israeli Prime Minister Benjamin Netanyahu over the phone Sunday to discuss a potential hostage and cease-fire deal along with other demands as the assault in Gaza continues.

On Sunday, the White House said Biden inquired about the likelihood of a deal with Hamas to release the remaining Israeli hostages in exchange for an immediate cease-fire in Gaza, talks which have slowed in recent weeks. Secretary of State Anthony Blinken is heading to Israel this week to assist with reigniting the discussions.

Officials said Biden also used the call to reaffirm his stance against a ground invasion of Rafah, the southern Gaza city where the majority of the population is now located after the Israeli offensive. Biden has said he is against the invasion given the likelihood of increasing civilian casualties during a conflict that has already killed more than 33,000 people, though Netanyahu appears to be in favor of proceeding with it.

The two also discussed humanitarian aid for civilians in Gaza, who face dangerous conditions amid the Israeli blockade.

“The President and the Prime Minister also discussed increases in the delivery of humanitarian assistance into Gaza including through preparations to open new northern crossings starting this week,” the White House said in a statement.

Despite the tough tenor of the call, the White House said Biden remains “ironclad” in his support of Israel, especially in the aftermath of the drone and missile strike by Iran earlier this month.

The conversation between Biden and Netanyahu comes amid increasing domestic pressure to toughen his stance with Israel. Colleges across America are erecting Gaza solidarity encampments, leading to clashes with administrators, and elected officials are turning up their rhetoric against Israel’s tactics in Gaza. Sen. Bernie Sanders (I-Vermont) is among the latest to do so, describing Israel’s actions as “ethnic cleansing” during an appearance on CNN on Sunday.