WHEN BERNIE Sanders won the New Hampshire primary, he became the first Jew to win a major party presidential primary - the first to even win delegates.

But how Jewish is he? Who even knows he's Jewish? Will it matter that he's Jewish?

In the recent Milwaukee debate, when asked how he felt about possibly "thwarting history" by blocking the path of the first woman president, Sanders replied enigmatically that, "from a historical point of view, somebody with my background, somebody with my views" would also be a first. Not exactly playing the Hebrew National card.

Hillary Clinton makes frequent mention of gender in her candidacy. Sanders never volunteers anything about his religion, and reluctantly replies to those questions. Is it personal, tactical, or practical?

Two of the three previous Jewish candidates for president - Pennsylvania Sen. Arlen Specter in 1995 and Pennsylvania Gov. Milton Shapp in 1976 - were early flameouts, probably more because of policy and personality than religion. The same for Joe Lieberman, an Orthodox Jew who ran briefly in 2004. (Shapp, however, told friends he doubted he would have been elected governor under his obviously Jewish birth name, Shapiro, which he changed while in business to avoid prejudice.)

One person of Jewish ancestry was nominated: In 1964, Arizona Sen. Barry Goldwater got the Republican nod. Goldwater's father was Jewish, but the conservative senator was raised Christian. At the time, Jewish journalist Harry Golden quipped, "I always knew the first Jewish president would be an Episcopalian."

In the '90s, as a rising-star big-city mayor, Ed Rendell brushed off questions about presidential ambitions, saying he wasn't interested. He added, "Besides, I'm Jewish."

"Ed always said, 'I'm a Jew from Pennsylvania. It didn't work out for Shapp and Specter,' " political strategist Neil Oxman told me.

As chairman of the Democratic National Committee in 2000, Rendell said Al Gore's selection of Lieberman as a vice presidential candidate was "bold and courageous," but also risky.

"I don't think anyone can calculate the effect of having a Jew on the ticket," Rendell said. "If Joe Lieberman were Episcopalian, it would be a slam-dunk."

Have things changed since then?

Rendell said they have. "If I were 15 years younger, and Hillary wasn't in the race, I think I would run and I wouldn't feel any compunction about it," said Rendell, who is not religious.

It was a little different with Lieberman, a religious Jew who didn't work on Saturdays. "Bernie is much more like me," Rendell said. "Lapsed."

I doubt that most Americans know that Sanders, 74, is Jewish. If he manages to win the nomination, or gets really close, someone will tell them. And not in a helpful way.

I'm not even sure most Jews know that Sanders is Jewish. Local political consultant Larry Ceisler, who is Jewish, told me, laughing: "I never thought of him as one, but I do know he's from Brooklyn." Ceisler doubts that most Americans know Sanders is Jewish.

I'm not sure even Sanders knows he is Jewish.

Let me explain.

When talking about his upbringing, he always says that his father, Eli, was an immigrant from Poland, but rarely mentions that most of Eli's family perished in the Holocaust.

Some candidates brag on their bio, but Sanders is usually clam-tight about his personal life. We know he attended Hebrew school as a youth and became a bar mitzvah in 1954. On the campaign trail, he avoids talking about religion.

Often wrongly described as cranky, which is ageist and inaccurate, Sanders wants to be an "issues" guy and can be gruff when someone tries to inject what he regards as frivolities. (Personal disclosure: My daughter is a volunteer field organizer for Sanders in Massachusetts.)

When pressed, Sanders says he is Jewish, secular, not particularly religious. His second wife, Jane, is a divorced Catholic and, yes, they did honeymoon in the Soviet Union. (He was working on setting up a Sister City in Russia for Burlington, where he was the mayor.)

Richard Sugarman, an Orthodox Jew who teaches religious studies at the University of Vermont, was quoted in the New Yorker as saying that Sanders' connection to Judaism is "more ethnic and cultural than religious."

With his first wife, Sanders volunteered on Kibbutz Sha'ar HaAmakim, a collective farm in northern Israel. He doesn't talk about that, either. It was in the '60s and was a good fit because Israel was then largely socialist. He has not visited Israel since. It would be less comfortable now because Israel has developed a vibrant free-market economy. Sanders might not like that, nor the current conservative government.

I suspect that socialism is more his religion than Judaism, as was the case for my Jewish, socialist, Brooklyn-born father.

Tikkun olam, which means "repair the world" in Hebrew, is a concept that has come to mean that Jews are responsible not just for their own moral, material and spiritual welfare, but for the welfare of society at large. "Repairing the world" seems to be what animates Sanders.

His oratory has been likened to that of a biblical prophet, pointing at the sky and pounding the table when thundering about unequal wealth distribution, criminal justice, health care and education, campaign financing, climate change - his unruly white hair exploding above a face red with indignation. Remove the wire-frame glasses, add a beard and a staff, and you have Moses. Can this Moses reach the promised land of the White House?

I mean, can we have a Jewish president?

The open bias against Jews that existed in the United States through most of the 20th century - keeping them out of some communities, clubs, careers, colleges - has vanished from public view, although some lingering, low-level anti-Semitism exists and probably always will.

However, last summer a Gallup poll reported that 91 percent of Americans said they would vote for a Jewish president. That's higher than those who said they would vote for a Mormon (81 percent), an evangelical Christian (73 percent), a Muslim (60 percent) or an atheist (58 percent). That sounds good, but I suspect the numbers are biased to the positive because most people won't admit to their biases.

As to the Jewish vote in the general election, either Sanders or Clinton can count on - to borrow a word from Donald Trump - a huuuuge majority of the Jewish vote. The bulk of American Jewry is a subsidiary of the Democratic Party, with John F. Kennedy winning 82 percent of them in 1960. Only Jimmy Carter received less than half, 45 percent, in his 1980 reelection bid - but that was still more than the 41 percent of the total vote Carter received.

The Jewish love affair with the Democratic Party began with Franklin Delano Roosevelt, who appointed so many Jews to government posts that his New Deal was called the "Jew Deal" by bigots (some of whom insisted that FDR was Jewish. He was not.).

A Democratic candidate, Jew or gentile, can count on the bulk of the Jewish vote, but Jews are only 2 percent of the population.

Does being Jewish prevent Sanders from being elected?

My Jew crew doesn't think so.

Strategist Oxman, a secular Jew, said, "if Sanders does not win the nomination, less than 1 percent of it would be that he's a Jew."

Oxman, a Hillary supporter, said Clinton will win the nomination because she has the establishment on her side and because Sanders is a socialist, a term that most Americans find creepy.

Forget Jewish, "he's out of the mainstream," said Ceisler, another Clinton supporter. "It doesn't matter what the question is, the answer is always blame the millionaires and the rigged system."

The socialist label, Rendell said, is "a 50 times bigger problem" than his faith.

The days of Jews being barred from the White House are gone, Oxman said.

"Some people from the South, they might vote against him more because he's from New York than that he's Jewish," Oxman said.

Sanders is from New York. That may matter.

He's a socialist. That will matter.

He's Jewish. That may not matter - even after Americans find out.

215-854-5977 @StuBykofsky

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