JERUSALEM — The White House denounced Hamas’ response Saturday to a new U.S. ceasefire proposal as totally unacceptable and said it “only takes us backward” after the group sought firmer guarantees that the deal would lead to a permanent end to the war.

Under the U.S. proposal, which was floated by Steve Witkoff, President Donald Trump’s Middle East envoy, Israel and Hamas would halt the fighting in the Gaza Strip for at least 60 days, during which some hostages would be freed in exchange for Palestinians jailed by Israel. And there would be further U.S.-backed negotiations on a permanent end to the war.

That issue has long been the core sticking point in the truce negotiations. Hamas has been willing to free the remaining Israeli and foreign captives in Gaza in exchange for a guarantee of a lasting end to the war. Israel has vowed to fight until Hamas lays down its arms and sends it leaders into exile.

Witkoff laid the blame on Hamas for the impasse, saying in a statement that its response “only takes us backward.” He said Hamas should accept the U.S. framework as the basis for further intensive negotiations, “which we can begin immediately this coming week.”

A Hamas official outside Gaza had said earlier Saturday that the group was seeking amendments to the Witkoff proposal around the guarantees for ending the war decisively.

An Israeli official said Hamas had demanded stronger guarantees that the temporary truce would pave the way for the end of the conflict that began almost 20 months ago. Both the Israeli and the Hamas officials requested anonymity because of the sensitivity of the topic.

Although Israeli Prime Minister Benjamin Netanyahu says he is willing to reach a temporary ceasefire with Hamas to free hostages, he has ruled out ending the war unless the group meets Israel’s conditions — which the group has rebuffed for the time being.

U.S. officials and other mediators have tried to cobble together a new truce since Israel ended the last ceasefire with Hamas in mid-March. But they have struggled to overcome the basic divide in Israel’s and Hamas’ war aims.

Hamas said Saturday that it had submitted an answer to the proposal that aimed to achieve a permanent ceasefire, bring a full Israeli withdrawal from Gaza, and ensure the flow of aid to desperate and hungry Palestinians in Gaza. The wording indicated that the group was seeking more than the current proposal’s guarantee of a temporary pause in hostilities.

The group said if there was agreement, it would turn over 10 living hostages and the bodies of 18 in exchange for an agreed-upon number of Palestinian prisoners.