A tweet by Donald Trump claiming the alt-right hate figure, the Jewish billionare George Soros, was funding the angry protests against his embattled Supreme Court nominee Brett Kavanaugh has triggered a backlash accusing the the president of inciting anti-Semitism.

The incendiary tweet also employed another favored alt-right trope of "paid professionals" being used by shadowy liberal forces popularized by the Alex Jones' Infowars site, who has caused outrage and offense by asserting that the Sandy Hook massacre was a “false flag” and that “no one died”. He claimed that the children killed were acting for the cameras, and that the parents had faked their own childrens’ deaths.

Trump echoed this highly controversial right-wing conspiracy theory in his Kavanaugh tweet: "The very rude elevator screamers are paid professionals only looking to make Senators look bad. Don’t fall for it! Also, look at all of the professionally made identical signs. Paid for by Soros and others. These are not signs made in the basement from love!"

Financier George Soros, a Hungarian-born Jew who survived the Holocaust, has used his fortune to fund liberal causes worldwide through his Open Society Foundation and has been cast a demonic manipulator by the far-right in Europe and the USA. Critics have claimed the attacks reek of classic anti-Semitism.

In response social media was inundated with accusations that Trump had weaponized anti-Semitism to discredit the opposition to the Kavanaugh, who was accused of a high school sexual assault by Dr. Christine Blasey Ford, by women's groups, the MeToo movement and the Democratic Party.

Meanwhile, Republican U.S. Senator Jeff Flake, who forced an FBI probe of sexual assault allegations against Kavanaugh, said on Friday he would vote in favor of the judge's confirmation unless something big changes, MSNBC reported.

Flake voted earlier on Friday to advance Kavanaugh's nomination to a final vote in the Senate. That vote could take place as early as Saturday.

Byt U.S. Republican Senator Lisa Murkowski, who is considered a key vote in whether Kavanaugh is confirmed, said she had not made up her mind on what her final vote would be.

"This has truly been the most difficult ... decision that I've ever had to make," Murkowski told reporters. "I believe he's a good man. It just may be that in my view, he's not the best man for the court at this time."