Republican front-runner Donald Trump has vowed an unbreakable US alliance with Israel if he is elected president, seeking to clear up confusion over his repeated pledges to remain neutral in any peace negotiations between Israelis and Palestinians.
Trump's speech to the American Israel Public Affairs Committee, a pro-Israel lobby group, was part of a day-long effort by the anti-Washington candidate to persuade establishment Republicans to get behind his candidacy.
Describing Israel as ready to negotiate a peace agreement, Trump said the Palestinians would have to be willing to accept that Israel will forever exist as a Jewish state and be able to stop attacks on Israelis.
"The Palestinians must come to the table knowing that the bond between the United States and Israel is unbreakable," the New York billionaire said.
Trump has drawn fire for his position on Middle East peace negotiations. He has described himself as extremely pro-Israel, but has said he would take a "neutral" stance in trying to negotiate an elusive peace settlement between Israel and the Palestinians.
Trump's leading Republican rival, US Senator Ted Cruz, reminded the AIPAC gathering of Trump's position, and Democratic front-runner Hillary Clinton, a former secretary of state, used her AIPAC appearance to attack him.
"We need steady hands, not a president who says he's neutral on Monday, pro-Israel on Tuesday and who-knows-what on Wednesday because everything's negotiable," she said.
Clinton also took aim at Trump's vow that, if elected, he would deport illegal immigrants and bar Muslims temporarily from entering the US.
"If you see bigotry, oppose it, if you see violence, condemn it, if you see a bully, stand up to him," she said.
At a news conference, Trump presented himself as Republicans' best chance of capturing the White House in November.
Trump said establishment Republicans would be making a mistake if they persuade a high-profile party leader to launch a third-party run to deny him the White House, saying it would "almost certainly" mean the Democrats would win the presidency.
"If people want to be smart, they should embrace this movement," Trump said at the site of a new hotel he is building in Washington.
"If they don't want to be smart, they should do what they're doing now and the Republicans are going to go down to a massive loss."
Trump laid out some foreign policy priorities in a CNN interview, saying the US is contributing more than it should to the NATO alliance and he would continue a US thaw toward Cuba begun by President Barack Obama, who is now in Havana.
Trump was also in Washington for closed-door talks with a variety of Republicans organised by his top backer in the capital, US Senator Jeff Sessions of Alabama.
In a separate session with the Washington Post editorial board, Trump named members of his foreign policy team, including Walid Phares, who Trump called a counter-terrorism expert; George Papadopoulos, an oil and energy consultant; and Joe Schmitz, a former inspector-general at the Department of Defense.