Half a year after Democratic candidates all shunned the annual conference of AIPAC, the historic pro-Israel lobby, five candidates came in person to deliver a peace message in the same Washington convention center to J Street, a left-leaning group which argues that it is more in tune with American Jews.

Senator Bernie Sanders, who rarely talks about his Jewish faith, explained how the murder of much of his father's family in the Holocaust shaped his progressive views.

"If there is any people on earth who understands the danger of racism and white nationalism, it is certainly the Jewish people," Sanders said to thunderous applause.

Rising from his seat on stage to give a campaign-style address, Sanders, who would be the first Jewish president, accused both Trump and Israeli Prime Minister Benjamin Netanyahu of fomenting division.

"Let me underline this because it will be misunderstood -- it is not anti-Semitism to say that the Netanyahu government has been racist. It is a fact," he said.

"We demand that the Israeli government sit down with the Palestinian people and negotiate an agreement that works for all parties," he said.

Sanders said his message to Israel would be, "if you want military aid, you are going to have to fundamentally change your relationship" with the Palestinians.

He called for some of the $3.8 billion in annual military assistance to be turned into humanitarian aid for the Gaza Strip in a "radical intercession" for the packed, impoverished territory under a blockade since it elected Islamist militants Hamas in 2007.

"Who is going to deny that when youth unemployment is 60 percent, when people have no hope, when people cannot literally leave the region -- who can think for a moment that you're not laying the groundwork for continued violence?" he said.

- Reversing some Trump steps -

Trump, whose evangelical Christian base is staunchly pro-Israel, has taken a series of historic steps including recognizing bitterly disputed Jerusalem as Israel's capital.

The Trump administration has signaled a green light as Netanyahu -- whose political future is unclear after two inconclusive elections -- flirts with annexing parts of the West Bank.

Democratic frontrunners Joe Biden and Elizabeth Warren, both appearing before J Street in video messages, said they would oppose any action that closes the door on a Palestinian state.

"If Israel's government continues with steps to formally annex the West Bank, the US should make clear that none of our aid should be used to support annexation," Warren said.

Warren said that she would reverse several key measures of Trump -- by resuming aid to the UN refugee agency for Palestinians and allowing the Palestine Liberation Organization to unshutter its Washington office.

While not reversing course on the US embassy, she said she would reopen the US mission in east Jerusalem which would become an embassy if a peace deal creates a Palestinian state.

Biden, who had uneasy relations with Netanyahu while vice president, said: "We can't be afraid to tell the truth to our closest friends."

"The two-state solution is the best, if not the only, way to secure a peaceful future for a Jewish, democratic state of Israel," Biden said.

- Contrast with AIPAC -

In a scene unimaginable at AIPAC, the mostly Jewish crowd gave a standing ovation to chief Palestinian negotiator Saeb Erekat as he stood on stage to the sounds of U2's "Beautiful Day" and said of creating a Palestinian state, "Let's not give up."

With some 4,000 people in attendance, J Street still had less than a quarter of the turnout of AIPAC, which is itself non-partisan but this year drew a who's who of Republicans.

J Street president Jeremy Ben-Ami said he believed his organization was more in line with the US Jewish community, which votes overwhelmingly Democratic and, in his view, no longer wants to write "a blank check" to policies such as occupation.

Touching an especially thorny issue, candidate Julian Castro rejected bids to penalize supporters of the so-called BDS movement that calls for boycotts, divestment and sanctions on Israel.

"I don't support BDS, but I also don't support cracking down on political speech," he said.