Israeli far-rightist Itamar Ben-Gvir, a likely senior partner in the next coalition government, was booed on Thursday at a memorial service for Meir Kahane, founder of a Jewish militant group, when he disavowed its call for mass expulsion of Arabs.
A former member of Kahane's outlawed Kach movement, he tweeted ahead of the Jerusalem event that his participation was in recognition of the slain U.S.-born Israeli rabbi's "love of Israel" and "fight for Soviet Jewry and against anti-Semitism".
Israeli TV aired his eulogy for Kahane, who was shot by an Egyptian-American militant in Manhattan 32 years ago this week.
"It's no secret that today I am not Rabbi Kahane, and don't support expulsion of all the Arabs and will not pass laws for separate beaches for Arabs and Jews," he said, drawing boos from members of the audience, several of whom wore Kach T-shirts.
But there were cheers when he repeated his election pledge to deport "terrorists" - a term he has applied to Palestinian stone-throwers, as well as to some representatives of Israel's 21% Arab minority.
Ben-Gvir, 46 and a practicing lawyer, says he has moderated.
Having placed first in last week's election, conservative former Prime Minister Benjamin Netanyahu will almost certainly need to ally with Ben-Gvir's Religious Zionism and other nationalist parties to achieve a stable parliamentary majority.
That has raised alarm in Israel and abroad, given Ben-Gvir's record which includes a 2007 conviction for racist incitement and support for terrorism, and anti-LGBT activism.
Ben-Gvir wants the Palestinian Authority, which has limited rule in parts of the territory under interim U.S.-sponsored peace deals, dismantled.
Ben-Gvir also supports Jewish prayer on a flashpoint Jerusalem holy site that houses al-Aqsa mosque and which is a vestige of ancient Jewish temples.
"Celebrating the legacy of a terrorist organization is abhorrent. There is no other word for it," U.S. State Department Spokesperson Ned Price said. "We urge all parties to maintain calm, exercise restraint, and to refrain from actions that only serve to exacerbate tensions and that includes in Jerusalem."
"My job, as the American ambassador, is to keep the dialogue going ... but to push back on things that we disagree with. And I will be pushing back aggressively on things we disagree with," U.S. Ambassador to Israel Tom Nides said.