Netanyahu's White House visit, his first since before former President Donald Trump left office in 2020, comes at a time of growing pressure on all three to find an endgame to the nine-month war that's left more than 39,000 dead in Gaza. What's more, dozens of Israeli hostages --and the remains of others who have died in captivity -- are still languishing in Hamas captivity.

Biden is pressing to get Israel and Hamas to seal his proposal to release remaining hostages in Gaza over three phases -- something that would be a legacy-affirming achievement for the 81-year-old Democrat who abandoned his reelection bid earlier this week and endorsed Harris. It could also be a boon for Harris in her bid to succeed him.

White House officials say that the negotiations are in the closing stages, but there are still issues that need to be resolved.

Following their midday talks, Biden and Netanyahu will meet the families of American hostages.

Harris, who will meet separately with Netanyahu later, is trying to demonstrate that she has the mettle to serve as commander in chief. She's also being scrutinized by those on the political left who say Biden hasn't done enough to force Netanyahu to end the war and by Republicans looking to brand her as insufficient in her support for Israel.

A senior administration official, who briefed reporters on the condition of anonymity under ground rules set by the White House, said there is "no daylight between the president and vice president" on Israel. Harris' last one-on-one engagement with Netanyahu was in March 2021, but she's taken part in more than 20 calls between Biden and Netanyahu.

Netanyahu, meanwhile, is trying to navigate his own delicate political moment. He faces pressure from the families of hostages demanding a cease-fire agreement to bring their loved ones home and from far-right members of his governing coalition who demand he resist any deal that could keep Israeli forces from eliminating Hamas.

Netanyahu, in a fiery address before a joint session of Congress on Wednesday, offered a robust defense of Israel's conduct during the war and lashed out against accusations by the International Criminal Court of Israeli war crimes. He made the case that Israel, in its fight against Iran-backed Hamas, was effectively keeping "Americans boots off the ground while protecting our shared interests in the Middle East." The Israeli leader spent scant time discussing the ongoing negotiations.

"Remember this: Our enemies are your enemies," Netanyahu told American lawmakers. "Our fight, it's your fight. And our victory will be your victory. "

Netanyahu used his speech to praise Biden for his administration's support in the aftermath of the Oct. 7 attack on Israel. But Netanyahu also went out of his way to note action that Trump during his four years in office took that benefited Israel, including recognizing Israel's sovereignty over the Golan Heights, confronting Iran's aggression and moving the U.S embassy from Tel Aviv to Jerusalem. Netanyahu is set to travel to Florida on Friday to meet with Trump.

Netanyahu also slammed protesters who massed near the U.S. Capitol on Wednesday, calling them Iran's "useful idiots." U.S. Secret Service beefed up security at the White House ahead of Netanyahu's visit, erecting additional fencing and barriers near the White House campus.

Trump and his Republican allies criticized Harris, who had events in Indiana and Texas on Wednesday, for skipping Netanyahu's address to Congress.

The vice president is the presiding officer of the Senate and would typically co-preside over such an event with the House speaker. But there have been other instances in recent history when the vice president has skipped such addresses. Biden, as vice president, skipped an address Netanyahu made to Congress in 2015.

Harris "should be here whether she likes the prime minister of Israel or not, whether she respects him or not, she should be here," said Iowa Sen. Joni Ernst, who organized a news conference with fellow Senate Republicans that largely focused on Harris' absence from the speech. "It is a disgrace."

White House officials said that her absence wasn't a slight and was solely due to scheduling conflicts. Harris spoke on Wednesday to the historically Black sorority, Zeta Phi Beta, before flying to Houston ahead of an address to American Federation of Teachers on Thursday. Sen. JD Vance, the Republican vice presidential nominee, also skipped the speech to campaign.

"The vice president has been unwavering in her commitment to the security of Israel," White House press secretary Karine Jean-Pierre said.

Harris has long spoken of her strong support for Israel. The first overseas trip of her Senate career in early 2017 was to Israel and one of her first acts in office was to introduce a resolution opposing a U.N. Security Council resolution condemning Israel.

She's also spoken of her personal ties to Israel, including memories of raising money as a child to plant trees in Israel, installing a mezuzah near the front door of the vice president's residence in Washington (her husband is Jewish), and her connections to pro-Israel groups including the conservative American Israel Public Affairs Committee and the liberal J Street.

Harris has largely been in lockstep with Biden throughout the conflict, but at moments she's been a front-runner for tougher Biden administration rhetoric on Israel.

She used a high-profile address in March in Selma, Alabama -- one day before she met with Netanyahu rival and Israeli war cabinet member Benny Gantz -- to decry Palestinians "starving" in the face of "inhumane" conditions and to urge Israel to do more to alleviate civilian suffering in Gaza.

Last year, Israel's foreign minister Eli Cohen criticized Harris after she appeared to gently rebuke Netanyahu's planned overhaul of the country's judiciary. Speaking at an Israeli embassy event in Washington, Harris had said that shared values are "the bedrock of the U.S.-Israel relationship" and that democracies are "built on strong institutions, checks and balances, and, I'll add, an independent judiciary."

Cohen questioned if Harris had even read the bills in question, saying, "I can tell you that if you ask her what bothers her about the reform, she won't be able to tell you."

Critics of Biden's handling of the Gaza war will also be watching Harris' interaction with Netanyahu and what she has to say in the days to come about the conflict.

Voters in electoral battlegrounds where anger over Gaza has become a key issue are waiting to see if Harris will be "turning the page on Biden's disastrous policy," said Layla Elabed, a leader in the "uncommitted" movement of voters that has threatened to withhold support from Biden because of Gaza.

"We hope that Harris does the right thing to save lives and our democracy and uphold international American law," Elabed said.