Donald Trump has sparked outrage by appearing to use an anti-Semitic trope about Jews being "disloyal".
The US President said "any Jewish people that vote for a Democrat, I think it shows either a total lack of knowledge or great disloyalty."
He spoke after two Democratic Congresswomen, Rashida Tlaib and Ilhan Omar, for supporting a boycott of the country over its treatment of Palestinians.
The International Holocaust Remembrance Alliance says examples of anti-Semitism include holding Jews collectively responsible for Israel's actions, or assuming they have a higher loyalty to Israel.
David Harris of the American Jewish Committee described the remark as "inappropriate, unwelcome and downright dangerous".
Jonathan Greenblatt, the head of the Anti-Defamation League, said: "It’s unclear who the President is claiming Jews would be 'disloyal' to, but charges of disloyalty have long been used to attack Jews.
"As we’ve said before, it's possible to engage in the democratic process without these claims.
"It's long overdue to stop using Jews as a political football."
The Jewish Democratic Council of America tweeted: "Trump repeating anti-Semitic tropes, emboldening hate groups, & using anti-Semitism for political purposes make us less secure.
"Today’s remarks are another example of him weaponizing & politicizing anti-Semitism for perceived political gain."
The Council's executive director Halie Soifer added: "If this is about Israel, then Trump is repeating a dual loyalty claim, which is a form of anti-Semitism.
"If this is about Jews being 'loyal' to him, then Trump needs a reality check. We live in a democracy, and Jewish support for the Republican Party has been halved in the past four years."
Trump made the remarks in the White House, saying the two Congresswomen "hate Israel and hate Jewish people".
He added: "Omar is a disaster for Jewish people. I can't imagine if she has any Jewish people in her district that they could possibly vote for her."
But he neglected to mention his own encouragement of far-right groups, including saying in 2017 that a white supremacist protest in Charlottesville included "many fine people".
Democrat former Presidential hopeful Bernie Sanders said: "Let me say this to the President. I am a proud Jewish person. And I have no concerns about voting Democratic.
"And, in fact, I intend to vote for a Jewish man to become the next president of the United States."
