Vice President Biden hasn’t even gained the Democratic nomination and already the rush is on to get the party to formally turn against Israel. That is what we take from the letter to the party’s national committee from 30 former national security officials. They want the Democratic nominee to stand on a platform that opposes the annexation of Jewish settlements in Judea and Samaria. And Mr. Biden seems ready to oblige.

Existence of the letter was first reported Monday by the Huffington Post. It’s gained scant comment, as far as we can tell, save on the Jewish News Service. Yet the signatories include such figures as President Obama’s former deputy state secretary, Strobe Talbott, Mr. Clinton’s former ambassador to Israel, Martin Indyk, and the head of UNICEF, the children’s fund of the United Nations, Anthony Lake, another Clintonite.

What is shocking is that the signatories of the letter are not — or at least were not — radical upstarts of the ilk of the new crop of Democrats like Congresswomen Ilhan Omar and Alexandria Ocasio-Cortez. The leading signers were mainstream Democrats who, for the most part, served under Presidents Clinton and Obama and were embedded in various parts of the foreign policy-making apparatus throughout our government.

They served during years when everyone was warning that the Palestinian Arabs and Israel were facing the “last chance” to make peace under the terms of United Nationsl Resolution 242, which mandated a negotiation. The Arabs stood by their hatreds. Come a new American administration under President Trump, the train moved out of the station. And it’s not just the Israelis who are aboard.

One of the startling things is the willingness of the Arab countries themselves to wash their hands of the Palestinians and their refusal to accept Israel. We don’t want to make too much of that, but neither do we want to ignore it altogether. President Trump is offering his own peace plan. The Palestinians call it dead on arrival. It’s hard to see, though, where a policy of rejectionism is going to get them.

Politically here in America, this is but a chapter of a larger story. The letter from the 30 foreign policy professionals underscores how far away the Democratic Party has fallen from the bipartisanship that used to mark Middle East policy in America. The runner up in the Democratic primary this year, Senator Sanders, declared the Prime Minister of Israel a “racist” and the leading pro-Israel organization, Aipac, a platform for “bigotry.”

Mr. Biden aligned himself with J-Street, an opponent of Aipac. Following the letter from the Democratic foreign policy aides, the former vice president told the venerable Jewish Telegraphic Agency that if elected, he would resume American aid to the Palestinian Arabs. He’d also try to reopen the Palestine Liberation Organization’s office in Washington. He’d also reopen the U.S. consulate in East Jerusalem.

Those are all regressive steps, designed to roll back the policies that have made the Republicans the more pro-Israel of the two leading American political parties. And just when Israel itself, after an astonishing display of democracy has finally crafted a broadly based national government. In little more than a year, it took three free, unbridled, multi-party elections. That’s more than Israel’s enemies have held in decades. What a moment for the Democrats to turn their back.