Trump says 'no president' has helped Israel as much as he has

"I have been responsible for a lot of great things for Israel," Trump said when asked about his assertion that Jewish Americans who vote for Democrats show "a total lack of knowledge or great disloyalty."

Without specifically responding to accusations that he was promoting and politicising a well-known anti-Semitic trope, Trump said: "No president has ever done anywhere close to what I've done" for Israel.

The Republican leader cited as evidence his decision to move the US embassy from Tel Aviv to Jerusalem, and his recognition of Israeli sovereignty over part of the Golan Heights annexed by the Jewish state in 1981.

And once again, Trump accused US lawmakers including Palestinian-American Democrat Rashida Tlaib of being anti-Semitic.

"They are anti-Semites," he said in a long impromptu press briefing in front of the White House.

"In my opinion, if you vote for a Democrat, you're being very disloyal to Jewish people and you're being very disloyal to Israel," he said.

"In my opinion, the Democrats have gone very far away from Israel. I cannot understand how they can do that," Trump added.

Trump's comments late Tuesday about Jewish American voters prompted a wave of criticism, including from Jewish groups and Democratic lawmakers.

Those groups accused the president of anti-Semitism by questioning the loyalty of Jewish citizens - part of a longstanding trope accusing Jewish people of dual allegiance.

Presidential candidate and left-leaning independent Senator Bernie Sanders tweeted: "My message to Trump: I am a proud Jewish person and I have no concerns about voting Democratic."

Amid the simmering controversy, Trump on Wednesday wrote three tweets in which he quoted the comments of conservative radio host Wayne Allyn Root.

"'President Trump is the greatest President for Jews and for Israel in the history of the world (...) and the Jewish people in Israel love him like he's the King of Israel," the tweet said.

Trump wrote back: "Thank you to Wayne Allyn Root for the very nice words."

The hashtag #KingofIsrael was trending in the United States on Wednesday. 

Root who was one of the theorists who spearheaded a false theory that Barack Obama was not born in the US, something which would have disqualified him as president.