Washington has been increasingly critical of the mounting toll on civilians from more than nine months of war in the narrow coastal territory, while protests in Israel by families of hostages taken by Hamas are also causing headaches for Netanyahu at home.
The Israeli premier's visit comes at a time of political upheaval in the United States, with a gunman targeting Republican candidate Donald Trump, and President Joe Biden bowing out of the 2024 race for the White House and endorsing his deputy, Kamala Harris.
Prior to departing Israel on Monday, Netanyahu said he would "seek to anchor the bipartisan support that is so important for Israel" in his address to Congress.
"I will tell my friends on both sides of the aisle that regardless who the American people choose as their next president, Israel remains America's indispensable and strong ally in the Middle East," he said in a statement.
Biden will meet Netanyahu on Thursday, while Harris will hold separate talks with the Israeli leader. She will not, however, attend his speech due to previously scheduled travel.
Netanyahu will also meet with Trump -- with whose administration he had a much less fraught relationship than Biden's -- in Florida on Friday.
When he speaks on Wednesday, Israel's longest-serving premier will become the first foreign leader to address a joint meeting of the two chambers four times -- pulling ahead of Britain's Winston Churchill.
Speaker of the House Mike Johnson said Tuesday that with Israel facing attacks from various Iranian proxies, "it has never been more important than it is right now to stand with our closest ally in the Middle East."
'Should not be welcomed'
But Netanyahu has lost backing among some liberal lawmakers, including independent Senator Bernie Sanders, who said Tuesday that "Netanyahu should not be welcomed into the US Congress."
"On the contrary, his policies in Gaza and the West Bank and his refusal to support a two-state solution should be roundly condemned," Sanders wrote in a social media post, adding that he would not be attending.
Dick Durban, the number-two Democrat in the Senate, said he would also not be attending.
"I will stand by Israel, but I will not stand and cheer its current prime minister," he said in a statement.
Highlighting opposition to the Israeli leader, at least 200 people protested against Netanyahu's speech at a building in the US Capitol complex on Tuesday. Capitol police said they carried out arrests and had cleared the area.
Israel has recently intensified its attacks on Gaza and Netanyahu has insisted that only piling on military pressure can free the hostages and defeat Hamas, which launched a shock attack on October 7 that resulted in the deaths of 1,197 people, mostly civilians, according to an AFP tally based on Israeli figures.
Hamas militants also seized 251 hostages, 116 of whom are still in Gaza, including 44 the Israeli military says are dead.
Israel's retaliatory military campaign in Gaza has killed at least 39,090 people, also mostly civilians, according to figures from the Hamas-run territory's health ministry.
Publicly, Biden has voiced strong support for Israel. But he expressed concern over an offensive on the southern Gaza city of Rafah and suspended a shipment of 2,000-pound bombs to Israel over fears that they would be used in populated areas.
Despite the tensions, the United States has defended Israeli interests while taking a key role in mediation efforts, and the countries' military relationship remains strong, officials say.
But Council on Foreign Relations Middle East specialist Steven Cook said that "never before has the atmosphere been so fraught."
"There is clearly tension in the relationship, especially between the White House and the Israeli prime minister," Cook said.
