A group of five Democratic senators called on Secretary of State Marco Rubio to push Israel for increased humanitarian aid to Gaza, specifically infant formula, as reports circulate that Israel will slow or altogether stop aid into parts of northern Gaza.

“We write to you today asking that the United States use its full power and authority to immediately facilitate a massive surge in all humanitarian aid, and in particular infant formula, into Gaza to address this crisis,” the group of Democrats wrote in a Friday letter to Rubio. “The United States and Israel, have a moral obligation to address the dire conditions that threaten the lives of Palestinian families.”

The letter was signed by Democratic Sens. Ruben Gallego (Ariz.), Tim Kaine (Va.), Peter Welch (Vt.) Mark Kelly (Ariz.) and Elizabeth Warren (Mass.)

The group in its plea cited aid shortages they said are resulting from the Israeli government’s system of aid delivery, the Gaza Humanitarian Foundation (GHF), “which has resulted in a catastrophic decrease in food supplies and other humanitarian aid.”

The senators wrote that GHF aid packages don’t include baby formula, and while aid distributed by the United Nations does include baby formula, “an average of 69 trucks per day have entered Gaza according to Israeli government data—vastly below the 500 to 600 trucks per day the U.N. says are needed to meet humanitarian needs. As a result, Gaza is currently facing a dire shortage of baby formula, depriving infants of what is their only hope against starvation.”

The letter called on Rubio to demand that the Israeli government immediately “facilitate a massive surge of humanitarian aid to enter Gaza” and reopen all crossing points.

An official said Saturday that Israel plans to decrease aid to Northern Gaza, including halting airdrops over Gaza City and limiting aid truck entry, reports the Associated Press. Israel put an end to temporary daytime pauses in fighting to facilitate aid delivery on Friday, the AP noted.

House Democrats recently issued a similar statement of concern to Rubio, calling on the Trump administration to allow Palestinian children injured in the Israel-Hamas war to seek emergency medical care in the U.S. Their letter followed a recent decision by the State Department to halt the issuance of visas for people from Gaza, including medical-humanitarian visas.

“It is wrong to prevent children who are caught in the middle of this horrific conflict from receiving lifesaving medical care,” the lawmakers wrote in the Monday letter, which was signed by more than 140 House Democrats.

The Hill has contacted the State Department for comment.

Mike Lillis contributed to this report.