Netanyahu is assured a warm welcome from Republican lawmakers who arranged his speech in the House chamber, an appearance making him the first foreign leader to address a joint meeting of Congress four times, surpassing Winston Churchill.

But many Democrats and independents plan to boycott his appearance. The most notable absences will be behind Netanyahu as Vice President Kamala Harris, who serves as president of the Senate and traditionally would sit behind whatever dignitary is speaking, says a long-scheduled trip will keep her away.

The Vermont senator Bernie Sanders has condemned Netanyahu’s upcoming address to the US Congress, calling him a “war criminal” presiding over a “rightwing extremist government”.

“It will be the first time in American history that a war criminal has been given that honor.”, Sanders said on the Senate floor on Tuesday, asserting that Netanyahu “should not be welcome in the United States Congress.”

The next Democrat in line, Sen. Patty Murray of Washington, is declining to attend.

Senior Democratic lawmaker Jerrold Nadler called Netanyahu “the worst leader in Jewish history .”

However, Nadler, the Jewish representative from New York, announced he will still attend Netanyahu’s speech, saying “I feel my voice is more impactful in the room, holding the Prime Minister accountable".

Republicans targeted the absence of Harris — the new Democratic front-runner for the presidency — as a sign of disloyalty to an ally. But Donald Trump's running-mate, JD Vance, said campaigning would also make him a no-show for the Israeli leader's speech.

House Speaker Mike Johnson warned of a “zero-tolerance policy” for any signs of disturbances in the Capitol building.

Johnson arranged the address, an honor that marks both the two countries’ historically warm bonds and the political weight that support for Israel has long carried in U.S. politics.

Many Democrats who support Israel but have been critical of Netanyahu see the address as a Republican effort to cast itself as the party most loyal to Israel and to provide the prime minister with a much-needed political reprieve.

“I don’t know all the motivations for Speaker Johnson initiating the invitation but clearly he wanted to throw a political lifeline to Netanyahu whose popularity is very low in Israel right now,” Sen. Chris Van Hollen, among the dozens of Democrats set to boycott, said Tuesday.

Netanyahu also is to meet with Biden and Harris on Thursday, and Trump at Mar-a-Lago on Friday.

The United States is Israel's most important ally, arms supplier, and source of military aid. Netanyahu's visit is his first abroad since the war on Gaza started, and comes under the shadow of arrest warrants sought against him by the International Criminal Court over alleged Israel war crimes against Palestinians. The United States does not recognize the ICC.

ICC prosecutor Karim Khan said crimes against humanity allegedly carried out by Israel were part of "a widespread and systematic attack against the Palestinian civilian population pursuant to State policy."

Evidence Khan's office collected showed Israel had systematically deprived civilians of "objects indispensable to human survival" including food, water, medicine, and energy, he said. 

Netanyahu says his aims for the U.S. visit are to press for freeing captives held in Gaza, to build support for continuing Israel's war, and to argue for continuing to confront Hezbollah in Lebanon and Iranian-allied groups in the region. 

Netanyahu in his speech also may address a new China-brokered deal between Palestinian factions Hamas and Fatah to form a government together.

The agreement was an attempt to resolve a rivalry between the Palestinians groups, to secure a governing Gaza whenever the war ends. Israel immediately denounced the pact, and State Department spokesman Matthew Miller called Hamas a terror group that should have no role in governing Palestinians.

Some Democrats are wary about Netanyahu, who used a 2015 joint address to Congress to denounce then-President Barack Obama's pending nuclear deal with Iran. National Security Adviser Jake Sullivan has said he does not expect Wednesday's speech to be a repeat of 2015's.

As the prime minister speaks, multiple protests are planned in and around the Capitol. The largest is set for Wednesday morning, with organizers planning to march around the Capitol demanding Netanyahu’s arrest on war crimes charges.