WASHINGTON — The specter of Bernie Sanders loomed large over this year’s pro-Israel AIPAC conference — powerful Jewish leaders painting a doomsday scenario around the man who could be the first Jewish president.

The Vermont senator’s decision to boycott the meeting — once a crucial soapbox for presidential wannabes — also rankled Jewish voters at the event who blasted him for fostering growing anti-Semitism in the Democrat Party, they said.

“He is bad news,” Malcolm Sherman, a retired math professor from Albany, New York, told The Post. “He is not a friend of Israel.”

The 78-year-old sparked a feud with the American Israel Public Affairs Committee last week when he claimed it provided a platform “for leaders who express bigotry and oppose basic Palestinian rights.”

Israel’s Ambassador to the United Nations Danny Danon told the crowd of 20,000 gathered at the conference on Sunday that Sanders was an “ignorant fool.”

“We don’t want Bernie Sanders at AIPAC. We don’t want him in Israel,” Danon said.

“Anyone who calls our prime minister [Benjamin Netanyahu] a racist is either a liar, ignorant fool, or both,” he added.

Incoming AIPAC president Betsy Berns Korn warned that attacks to the US-Israel relationship were no longer coming from the fringes and were now “being led by those growing in power and influence.”

“Those who stand against the US-Israel relationship must know that the pro-Israel community will work to defeat them,” Korn said in what appeared to be a warning shot to Sanders. “We’re in a fight,” she cautioned.

Howard Kohr, the longtime executive director of AIPAC, also opened this year’s conference with a thinly-veiled shot at Sanders.

“Any leader who energizes their political movement by demonizing Israel is not a friend of Israel,” he said.

Sanders identifies himself as Jewish but has close ties to firebrand Reps. Rashida Tlaib and Ilhan Omar and activist Linda Sarsour — all supporters of the international BDS movement to boycott Israel — and that troubles many Jewish voters.

Sherman said he was concerned the Democratic Party was becoming increasingly hostile toward Israel and those who support it.

“It’s the kind of anti-Semitism where Jews are welcome, so long as they’re leftist, and they share their overall woke agenda,” he said.

“I don’t want Sanders to get the nomination because I don’t want the Democrats to go in that direction.”

In a tweet, Sanders blasted the conference he has never attended, unlike many of his Democrat and Republican colleagues on Capitol Hill who agree US support of Israel is a bipartisan issue.

“The Israeli people have the right to live in peace and security. So do the Palestinian people,” Sanders wrote last Sunday. “I remain concerned about the platform AIPAC provides for leaders who express bigotry and oppose basic Palestinian rights. For that reason I will not attend their conference.”

“As president, I will support the rights of both Israelis and Palestinians and do everything possible to bring peace and security to the region,” he vowed.

AIPAC has been accused of moving increasingly to the right and has been blasted for its support of Israeli Prime Minister Benjamin Netanyahu who is facing corruption charges.

Rabbi Jonathan Hecht of Cincinnati, Ohio, told The Post he identifies as a Liberal Democrat supportive of a two-state solution and said he was disappointed by Sanders’ decision not to attend.

“I’m very much pained by the decision that he views this as a place for bigotry,” Hecht said, calling the boycott “problematic.”

“This is a place to exchange ideas and views and not coming here is a statement that he’s not willing to engage in that kind of dialogue with Americans of all kinds.”