"Eliminating the threat posed by Hamas and protecting civilians are not mutually exclusive aims. Indeed, International Humanitarian Law requires that civilians be protected during armed conflict," a group of Democratic senators wrote in a letter to Biden.

The letter was led by Senators Tammy Baldwin, Tim Kaine and Chris Van Hollen, and signed by at least eight other Senate Democrats. The White House did not immediately respond to a request for comment.

The lawmakers sent the letter as Biden's administration said it was nearing a deal to free some of the 240 hostages taken by Hamas militants during a deadly cross-border rampage from Gaza into Israel on Oct. 7.

About 1,200 people were killed in that assault, according to Israeli tallies. Since then Gaza's government has said at least 13,300 Palestinians have been killed by Israeli bombardment. The United Nations says two thirds of Gaza's 2.3 million people have been made homeless.

The crisis has divided Congress, prompting to date only about three dozen Democratic members to back calls for a ceasefire, which Israel rejects as something that let Hamas regroup.

Monday's letter did not call for a ceasefire, but did note the dire humanitarian situation, including working toward the sustained delivery of water, food, fuel and other basic necessities, including by reopening the Kerem Shalom border crossing between Israel and Gaza, protection of civilians and civilian sites and ensuring civilians' access to medical attention.

"We are concerned that increased and prolonged suffering in Gaza is not only intolerable for Palestinian civilians there but will also negatively impact the security of Israeli civilians by exacerbating existing tensions and eroding regional alliances," the lawmakers wrote.

U.N. aid chief Martin Griffiths last week implored Israel to allow humanitarian aid into Gaza via the Kerem Shalom crossing.