“A country as small as Israel, facing our magnitude of threats, cannot be that picky about the way other countries decide to govern themselves,” he began. But, he added, “we also have a moral duty. I pushed forward in the last Knesset a recognition of the Armenian Holocaust even though this is not the right practical move opposite the Turks. Because there is a point where you say enough is enough.”

He was far more careful when I turned to the subject of Donald Trump. “I am, like any other Israeli, thankful for President Trump. I sat at the opening of the Embassy in Jerusalem with tears in my eyes,” he said.

What of Mr. Trump’s recent flurry of statements about how the Democratic Party has become anti-Israel and anti-Jewish? “I’m going to say this as politely as I can,” Mr. Lapid said. “He was wrong. I don’t think you can say that Eliot Engel and Jerry Nadler and Ted Deutch and Chuck Schumer don’t like Israel. They are the most pro-Israel people I know.” Mr. Lapid said one of his priorities if he wins would be to rebuild support for Israel among progressives. “Israel must be a bipartisan issue,” he said.

One of the casualties of Israel becoming an increasingly partisan issue has been American Jews themselves, who vote overwhelmingly Democratic and who see Israel’s rightward turn as betraying fundamental liberal values. In other words, American Jews find themselves stuck between B.D.S . — the boycott movement against Israel — and Bibi.

“I understand the fact that some kind of gap was opened between Israel and the diaspora,” Mr. Lapid said of this problem. “I think what unites us — culturally, morally — is way bigger than what separates us. And what we need to go back to is this vocabulary of one people.”

It is when Mr. Lapid talks about Jewish values and Jewish history that he is the most compelling. Doubly so when it comes to the subject of his father, Tommy Lapid, a Holocaust survivor who built a life in Israel as a journalist and then as a politician, and died in 2008.

“My father had a friend in the Budapest ghetto. His name was Thomas Lantos,” Mr. Lapid said. “After the Holocaust, they went to the same pier in the same harbor and Tom took a boat and went left and my dad took a boat and went right.” Mr. Lantos eventually ended up in California, where he became a Democratic member of the House of Representatives and head of the Foreign Affairs Committee. “They always felt that if they took the opposite boat, Tom would be the minister of justice and my father would be the head of the foreign committee.”