JERUSALEM — Two religious-Zionist parties withdrew from Israel’s governing coalition Monday, narrowing Prime Minister Benjamin Netanyahu’s working majority to a single seat as the Knesset voted to open a formal commission of inquiry into the six-week war with Iran.

The departure of Otzma Yehudit and a smaller breakaway faction of National Religious Party lawmakers came five days after the U.S.-brokered ceasefire took effect, ending a conflict that killed an estimated 4,200 Iranians and more than 380 Israelis and left large stretches of Tel Aviv, Haifa and the lower Galilee in need of reconstruction. The parties cited what they called the “premature” end of the campaign and the government’s decision to enter a Doha prisoner exchange on Saturday.

“This government surrendered at the threshold of victory,” Itamar Ben-Gvir, the former national security minister whose party led the walkout, told reporters outside the Knesset. “We will not provide cover for it.”

The commission of inquiry, approved 71-46 in a vote that drew support from opposition leader Yair Lapid’s National Unity bloc and from defectors within Likud, will examine intelligence failures in the run-up to the war’s opening week, civil-defense gaps that left coastal cities exposed to Iranian ballistic strikes through the first 10 days, and the chain of decisions surrounding two contested Israeli operations against Iranian nuclear sites near Natanz and Fordow.

Retired Supreme Court Justice Esther Hayut has been asked to chair the panel, according to a senior Knesset official who described the selection process on condition of anonymity because no formal announcement had been made. Hayut, who led the inquiry into the 2023 judicial-overhaul crisis, has not publicly responded.

Netanyahu, who addressed the nation Monday evening from the Prime Minister’s Office in Jerusalem, defended the war’s conduct and the terms that ended it. He called the ceasefire “a victory paid for at terrible cost” and said the inquiry would “demonstrate, in the end, what Israelis already know — that this country defended itself and prevailed.”

But the prime minister now governs with a 61-seat majority in the 120-seat Knesset, dependent on a single ultra-Orthodox lawmaker whose own party has signaled it may revisit its support pending a vote, expected next month, on emergency reconstruction financing. Two senior Likud figures have publicly floated the possibility of new elections before the High Holidays in September.

“The arithmetic is precarious and everyone in the building knows it,” said Yonatan Freilich, a political analyst at the Israel Democracy Institute. “Bibi’s calculation has always been that he survives because no one wants the election. That calculation is being tested in a way it has not been tested since 2019.”

The political turmoil unfolded against a still-fragile security backdrop. Israeli officials reported a rocket launched from western Iraq on Sunday evening fell harmlessly in open desert north of Eilat; the Iraqi government condemned the launch and attributed it to a splinter faction of Kataib Hezbollah. The Israel Defense Forces said it would respond “at a time and place of its choosing” but emphasized the ceasefire framework remained in effect. UN observer teams deployed to the Strait of Hormuz on Friday reported no incidents at sea over the weekend.

In Tehran, state media gave the Israeli political crisis prominent coverage, framing the inquiry as confirmation of Iranian claims that the war had been a strategic failure for the Netanyahu government. Iranian Foreign Minister Abbas Araghchi, speaking at a Tehran press conference, said his government “welcomes any honest accounting” of the war but rejected what he called attempts to relitigate the ceasefire’s terms.

The reconstruction picture remains daunting. A preliminary assessment released Sunday by Israel’s Ministry of Finance put direct damage to housing, infrastructure and commercial buildings at between 78 billion and 92 billion shekels, or roughly $21 billion to $25 billion. About 14,000 housing units have been judged uninhabitable across the Tel Aviv metropolitan area, Haifa and the Galilee corridor. Finance Minister Bezalel Smotrich, whose own coalition position has weakened, has proposed a one-time defense surcharge on incomes above 600,000 shekels to fund the early phase.

Public anger appears to be running ahead of the politics. A poll released Monday by the Hebrew daily Yedioth Ahronoth, conducted over the weekend, found 64 percent of Israelis supported a commission of inquiry and 52 percent said new elections should be held within the year. Only 31 percent said Netanyahu should remain prime minister through the rest of his term, which runs through 2027.

Among reservists and families of those killed, frustration has crystallized around the question of why Israeli civilians remained without reinforced shelter access in several neighborhoods of Bat Yam and southern Tel Aviv as late as the war’s second week. Two protest movements that gained traction during the war — one led by bereaved families, another by reservists — staged a joint rally outside the Defense Ministry on Sunday night drawing what organizers said was more than 80,000 people. Police estimates were lower.

“We did not ask for an inquiry to take down a government,” said Tamar Eldad-Cohen, 47, whose son was killed in a missile strike on a Haifa naval base in late March. “We asked for an inquiry because we deserve answers. If the government falls, that is not our doing. It is the doing of the people who made the choices.”

Israeli officials said the commission’s working timeline would likely extend 12 to 18 months, with interim findings expected before the end of the year. The Biden-era convention of releasing key documents to inquiries has been retained, a senior Justice Ministry official said. Hearings would begin once the chair was formally seated.