Senator Chuck Schumer, Democrat of New York and the majority leader, on Thursday delivered a pointed speech on the Senate floor excoriating Prime Minister Benjamin Netanyahu of Israel as a major obstacle to peace in the Middle East and calling for new leadership in Israel, five months into the war.

Many Democratic lawmakers have condemned Mr. Netanyahu’s leadership and his right-wing governing coalition, and President Biden has even criticized the Israeli military’s offensive in Gaza as “over the top.” But Mr. Schumer’s speech amounted to the sharpest critique yet from a senior American elected official — effectively urging Israelis to replace Mr. Netanyahu.

“I believe in his heart, his highest priority is the security of Israel,” said Mr. Schumer, the highest-ranking Jewish elected official in the United States. “However, I also believe Prime Minister Netanyahu has lost his way by allowing his political survival to take precedence over the best interests of Israel.”

He added: “He has been too willing to tolerate the civilian toll in Gaza, which is pushing support for Israel worldwide to historic lows. Israel cannot survive if it becomes a pariah.”

Mr. Schumer’s speech was the latest reflection of the growing dissatisfaction among Democrats, particularly progressives, with Israel’s conduct of the war and its toll on Palestinian civilians, which has created a strategic and political dilemma for Mr. Biden. Republicans have tried to capitalize on that dynamic, hugging Mr. Netanyahu closer as Democrats repudiate him.

In response to Mr. Schumer, Senator Mitch McConnell of Kentucky, the minority leader, said on the Senate floor that it was “grotesque and hypocritical” for Americans “who hyperventilate about foreign interference in our own democracy to call for the removal of the democratically elected leader of Israel.” He called the move “unprecedented.”

“The Democratic Party doesn’t have an anti-Bibi problem,” Mr. McConnell said, referring to Mr. Netanyahu by his nickname. “It has an anti-Israel problem.”

Mr. Schumer’s remarks came a day after Senate Republicans invited Mr. Netanyahu to speak as their special guest at a party retreat in Washington. Senator John Barrasso of Wyoming, the No. 3 Republican, asked Mr. Netanyahu to address Republicans virtually, but he could not appear because of a last-minute scheduling conflict. Ambassador Michael Herzog, Israel’s envoy to the United States, spoke in his place.

On Thursday, Mr. Schumer, who represents a state with more than 20 percent of the country’s Jewish population, was careful to assert that he was not trying to dictate any electoral outcome in Israel. He prefaced his harsh criticism of Mr. Netanyahu with a long defense of the country, which he said American Jews “love in our bones.”

Mr. Schumer said there had been an “inaccurate perception” of the war that lays too much blame on Israel for civilian deaths in Gaza without focusing enough on how Hamas uses Palestinian civilians as human shields. And he acknowledged how difficult it was for traumatized Israelis to contemplate the possibility of a two-state solution at this time.

But he was unsparing in his criticism of Mr. Netanyahu, calling the prime minister one of the top obstacles to achieving peace in the Middle East, along with Hamas, “radical right-wing Israelis” and Mahmoud Abbas, the president of the Palestinian Authority, who he also said should be replaced.

“The Netanyahu coalition no longer fits the needs of Israel after Oct. 7,” Mr. Schumer said. “The world has changed — radically — since then, and the Israeli people are being stifled right now by a governing vision that is stuck in the past.”

Mr. Schumer said the only solution to the decades-old conflict was a two-state solution: “a demilitarized Palestinian state living side by side with Israel in equal measures of peace, security, prosperity and dignity.” He said Mr. Netanyahu, who has rejected the idea of Palestinian statehood, was jeopardizing Israel’s future.

“At this critical juncture, I believe a new election is the only way to allow for a healthy and open decision-making process about the future of Israel, at a time when so many Israelis have lost their confidence in the vision and direction of their government,” Mr. Schumer said, adding that he believed a majority of the Israeli public “will recognize the need for change.”

“As a democracy, Israel has the right to choose its own leaders, and we should let the chips fall where they may,” he said. “But the important thing is that Israelis are given a choice. There needs to be a fresh debate about the future of Israel after Oct. 7.”

Mr. Schumer’s speech was the second time since Oct. 7 that he has taken to the Senate floor to address the Israeli-Hamas war. The conflict has prompted him to think more deeply and speak more openly about his Jewish faith and heritage, as well as the moral and political dilemmas the war has presented for Jews in Israel and the United States.

In November, Mr. Schumer made a deeply personal speech condemning the rise of antisemitism in America that has flared since Israel began retaliating against Hamas for its Oct. 7 terrorist attack against defenseless Israeli civilians. Those remarks appeared to be mostly directed at members of his own party; he warned that some liberals and young people were “unknowingly aiding and abetting” antisemitism in the name of social justice. Mr. Schumer has since spoken to publishers about writing a book on antisemitism.

On Thursday, his speech was aimed squarely at Mr. Netanyahu and far-right members of his governing coalition, who Mr. Schumer said were falling short of Jewish values.

Mr. Herzog had a stern response. “Israel is a sovereign democracy,” he wrote on social media. “It is unhelpful, all the more so as Israel is at war against the genocidal terror organization Hamas, to comment on the domestic political scene of a democratic ally.”

In his remarks, Mr. Schumer said that Mr. Netanyahu refused to “disavow Ministers Smotrich and Ben-Gvir and their calls for Israelis to drive Palestinians out of Gaza and the West Bank.”

“He won’t commit to a military operation in Rafah that prioritizes protecting civilian life,” Mr. Schumer said. “He won’t engage responsibly in discussions about a ‘day after’ plan for Gaza, and a longer-term pathway to peace.”

Mr. Schumer said that if Mr. Netanyahu and his current coalition remained in power, “then the United States will have no choice but to play a more active role in shaping Israeli policy by using our leverage to change the present course.”

Underscoring how contentious the issue of Israel is in American politics, Mr. Schumer’s speech was criticized by both the right and the left.

Layla Elabed, the campaign manager for Listen to Michigan, an antiwar group of activists who voted “uncommitted” in the state’s Democratic presidential primary, said that “Senator Schumer is beginning to shift but far too slowly and with little substance for what actions Biden can take now to stop the outrageous civilian death toll in Gaza.”

Nicholas Fandos contributed reporting.