“Ironclad,” said Joe Biden. “Ironclad,” said Lloyd Austin, the defense secretary. “Ironclad,” said the Senate leader Chuck Schumer, the House leader Hakeem Jeffries and the Michigan governor, Gretchen Whitmer.In the wake of Saturday’s attack by Iran, Democrats united around a single word in expressing their commitment to Israel’s security. It was a sentiment that papered over, at least for now, cracks in the party over Biden’s handling of the war in Gaza.But Biden’s renewed embrace of Israel could deepen further a row over US support for Israel’s war in Gaza that has engulfed the Democratic party and pitted the White House against its progressive wing – a split that could sap Biden’s support in November’s crucial presidential election.These have been trying weeks for the US president. As Gaza’s death toll climbs and famine looms, criticism of Israel’s conduct of the war has been growing from the left and even the centre, with some calling for an end to US arms supplies.Tens of thousands of people registered “uncommitted” protest votes against Biden in the Democratic primary election, including in swing states such as Michigan and Wisconsin, a grim portent ahead of the presidential election against Donald Trump in November.This pressure, and the recent deaths of World Central Kitchen aid workers in Gaza, seemed to finally prompt a shift in Biden’s tone. Last week he branded Israel’s handling of the war a “mistake”. Even then he remained passive-aggressive, declining to impose any tangible consequences.Then, on Saturday, Iran launched hundreds of drones and missiles at Israel on Saturday night in response to a suspected Israel attack on Iran’s Syria consulate on 1 April. Biden, cutting short a weekend stay at his Delaware beach house to meet with his national security team at the White House, was back in his instinctive comfort zone. His entire political career has been shaped by the view of Israel as a vulnerable ally in a hostile neighborhood that needs unequivocal US support.In an instant, the atmospherics in Washington changed. Schumer, who surprised many last month by calling for new elections in Israel, issued a statement that said “we stand shoulder to shoulder with the people of Israel” and made no mention of Gaza.The Democratic senator John Fetterman, no friend of pro-Palestinian protesters, told CNN’s State of the Union: “It really demonstrates how it’s astonishing that we are not standing firmly with Israel and there should never be any kinds of conditions on all of that. When a nation can launch hundreds of drones towards Israel, I’m not going to be talking about conditions, ever.”And on NBC’s flagship Meet the Press, John Kirby, the White House National Security Council spokesperson, gushed over “an incredible military achievement by Israel and quite frankly the United States and other partners that helped Israel defend itself against more than three hundred drones and missiles”.He added: “And I think Israel also demonstrated that it has friends, that it’s not standing alone, that it’s not isolated on the world stage.”Republicans seized on the attack to accuse Biden of weak leadership, claiming that only Trump could restore peace and stability to the world. Senator Marsha Blackburn of Tennessee called for “aggressive retaliatory strikes on Iran”.If they succeed in shifting the terms of the debate, it will be even harder for the president to signal a break from Netanyahu. Amid the drumbeat for rallying against a common foe, Democrats who call for military aid to be conditioned will be accused of tone deaf appeasement.On Sunday, the Washington news agenda was dominated by speculation over Biden can dissuade Netanyahu from striking back – “Take the win,” he reportedly said – and prevent a wider regional war, and whether Congress might now pass military aid for both Israel and Ukraine.Gaza – where Israel’s offensive has killed at least 33,729 people, mostly women and children, according to the territory’s Hamas-run health ministry – was no longer uppermost in the thoughts of politicians or the journalists who interview them.Progressives and protesters had come a long way in forcing Biden to question his most deeply held convictions and warn Netanyahu that enough is enough. The events of Saturday night shook the kaleidoscope yet again and may give the US president a different political and electoral calculus, an excuse to return to his default position. Yet people in Gaza are still dying, and many would-be Biden supporters are still angry about it. More