The 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.

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 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 attack.

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.”

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.”

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