Live updates: Follow the latest news on Israel-Gaza
Senate Middle East subcommittee chairman Chris Murphy called the lack of a post-war plan in Gaza “extraordinary".
Senator Tim Kaine worried that Washington is “losing credibility” over humanitarian aid deliveries into Gaza.
And Senator Chris Van Hollen questioned the integrity of US policy over the lack of sanctions against Israel's far-right Finance Minister, Bezalel Smotrich.
All of this criticism on Tuesday came from senior members of Joe Biden's own Democratic party, some of them close allies of the US President, directed at Washington's top Middle East diplomat.
The US assistant secretary for Near Eastern affairs, Barbara Leaf, spoke to the Senate foreign relations subcommittee on the Middle East on Tuesday, for a hearing meant to deal with the Biden administration's 2025 budget proposal.
But more imminent questions over Israel's war in Gaza dominated the hearing, as the administration continues to support Israel and ceasefire negotiations with Hamas remain at an impasse.
The scale of killing and destruction in Gaza has drawn an increasing number of establishment Democrats to criticise Israel, pressuring the Biden administration to turn words of condemnation against its ally into action.
Even amid growing tension with Prime Minister Benjamin Netanyahu, who on Tuesday criticised the US on claims that it was withholding military support, Ms Leaf told the committee: “This President has been clear … we absolutely have Israel's back.”
Mr Murphy said the administration's 2025 budget request “largely maintains recent funding levels for the West Bank and Gaza, even when we know we have a huge bill ahead of us”, and that Washington cannot effectively forecast its spending for Palestinians without a post-war plan.
“We are potentially weeks, maybe a month away from the formal military operations [in Gaza] coming to a close, and it is just extraordinary that we have no viable plan from the Israeli government as to what comes next,” he said.
The militant group in control of the Gaza Strip responded to a US-backed Israeli ceasefire proposal late last week, and the Biden administration has suggested that its counter-proposal may be “workable.”
Ms Leaf, who just returned from a regional trip with Secretary of State Antony Blinken and expects to leave again this weekend “to drill in deeper” on ceasefire negotiations, conceded “there is still insufficient planning, to say the least, on the part of the Israeli government.”
But she said “that has not kept us from doing the work on our side".
Washington has pledged to keep working with Qatar and Egypt for a deal to end the war, which has killed more than 37,300 Palestinians, Gaza health officials say.
Mr Kaine, another ally of Mr Biden, raised concerns that Israel's military campaign and pattern of slowing or blocking aid into Gaza “makes this look to many that it is not just a defence against Hamas, but that it is a larger effort to target Palestinians".
With critical land routes blocked, Washington has established a $320 million aid pier off Gaza's coast in a bid to increase humanitarian aid deliveries to the enclave.
Many in Gaza have been sceptical about the pier’s usefulness. Last month it was damaged by stormy seas.
Ms Leaf said that “Israel is not trying to impede” aid deliveries into Gaza, pointing to a “whole set of complex factors” including security conditions.
But Mr Kaine said: “When we render a conclusion that Israel is sufficiently co-operating with the United States on the delivery of humanitarian aid, at the same time we're having to spend hundreds of millions of dollars on a star-crossed effort to build an unworkable pier … I worry it makes us look like we lose our own credibility by blessing an effort that is thus far entirely insufficient.”
Republicans on Capitol Hill have maintained a steady stream of condemnation of the Biden administration's regional policy, which has long-predated the October 7 Hamas attacks on Israel in which 1,200 people died, and ensuing war in Gaza.
Under an intense round of questions from Republican Senator Ted Cruz, Ms Leaf asserted that “a series of black swan events” has hindered Mr Biden's goals for the Middle East.
“No doubt the region is in a very difficult state,” she said.
