The only Jewish candidate in the Presidential race will not address the annual meeting of the American Israel Public Affairs Committee (AIPAC).
Bernie Sanders announced his decision not to take part in the pro-Israel group's conference on Friday. He cited "travelling throughout the West" and "the campaign schedule" as reasons why he could not attend.
All the other presidential candidates will be appearing, including Republican frontrunner Donald Trump. The presence of the New York billionaire at the event on Monday has led at least 40 rabbis to boycott the conference.
However Sanders insisted his absence was not any form of boycott.
"I would very much have enjoyed speaking at the AIPAC conference," wrote Sanders in a letter to AIPAC head Robert Cohen.
"Obviously, issues impacting Israel and the Middle East are of the utmost importance to me, to our country and to the world," said Sanders.
The 18,000 delegates at the conference will instead receive a printed copy of the remarks Sanders would have said because AIPAC "has chosen not to permit candidates to address the conference remotely", he said in his letter.
Sanders' decision came after thousands signed a petition from a pro-Palestinian lobby urging the Democrat to turn down AIPAC's invitation.
A statement posted on the two petitions said Sanders "does not belong" in the conference which, it said, features "Islamophobes, anti-immigrant activists and religious extremists". Both petitions were launched by Max Blumenthal, a prominent activist who has opposed the Israeli occupation of Palestinian territories.
Sanders has said he "absolutely" supports Israel's right to exist and has also said the US should play "an even-handed role in terms of its dealings with the Palestinian community in Israel".
"The United States has got to work with other countries around the world to fight for Israel's security and existence at the same time as we fight for a Palestinian state where the people in that country can enjoy a decent standard of living, which is certainly not the case right now.
"My long-term hope is that instead of pouring so much military aid into Israel, into Egypt, we can provide more economic aid to help improve the standard of living of the people in that area."