Tens of thousands of demonstrators flooded Israel’s streets for a second straight night Sunday, calling for immediate elections and for the government to urgently negotiate the release of more than 100 hostages still held by Hamas in Gaza, the Washington Post reported.

The twin demands represented a merging of two distinct protest movements — one including the families of hostages, the other led by civil society and the political opposition — which could become the greatest threat yet to Prime Minister Benjamin Netanyahu and his far-right government.

On Sunday, the protesters moved from “Hostage Square” plaza in Tel Aviv to the parliament in Jerusalem, chanting for the removal of Netanyahu, the longest-serving leader.

Outside the Knesset, Carmi Paltzi Katzir, whose brother Elad Katzir was dragged into Gaza from Kibbutz Nir Oz on Oct. 7, decried what she said was the “failure of the government.”

“I would have never believed that after six months I would need to fight with the government for my brother’s right to return alive, or to return at all,” she said.

She cited testimonies from released hostages indicating that her brother, at least at first, had been to able to listen to the radio and watch television in captivity: “What does he think about us, as a society, about our prime minister?” she wondered.

The event on Sunday was the start of a four-day rally that organizers hope will either force the government to jump-start hostage negotiations — or lead to the collapse of Netanyahu’s coalition, the most right-wing in Israel’s history.

Netanyahu is already under growing pressure from Washington, Israel’s most important weapons supplier and diplomatic backer. American officials have expressed growing alarm about the war in Gaza, including Israel’s planned offensive in the southern city of Rafah, home to 1.4 million displaced Palestinians, and the humanitarian crisis in the north, where Israeli restrictions on aid deliveries have put hundreds of thousands of people on the brink of starvation.

Senate Majority Leader Charles E. Schumer (D-N.Y.) warned this month that Israel risked becoming an international “pariah” under Netanyahu’s leadership and urged the country to hold new elections. Netanyahu had been largely insulated from external pressure by an Israeli public that overwhelmingly supported the war and — until now, at least — had no appetite for wartime elections.