US President Joe Biden and Israeli Prime Minister Benjamin Netanyahu met on Thursday at the White House to discuss efforts to reach a ceasefire agreement in Gaza and the unfolding humanitarian crisis there.

The two leaders met in person for the first time since Biden visited Israel in October, less than two weeks after the Hamas attacks on October 7.

In welcoming Netanyahu, Biden said, "We've got a lot to talk about."

White House National Security Communications Advisor John Kirby suggested there are "gaps" between Israel and Hamas over a truce. However, he added that they are "closer" than ever before to an agreement.

Kirby said, "They believe, the president believes, that getting that hostage deal in place, getting that six-week ceasefire, that's the best way to get all these loved ones back with their families."

The leaders also met with the families of American hostages.

A father of one of the hostages said, "We feel probably more optimistic than we have since the first round of releases in late November, early December, when a little over 100 of Israel's hostages were released."

Protesters gathered outside the White House to express their anger over the conduct of Israeli forces in Gaza and Biden's support for Israel's war effort. They revisited their calls that Netanyahu should be arrested for war crimes.

Netanyahu also met Vice President Kamala Harris, Biden's successor as the Democrats presumptive nominee for president. A senior US official suggested the Israelis would see "full alignment" between Biden and Harris.

Netanyahu will travel to Florida on Friday to meet with former President Donald Trump.