U.S. Senator Elizabeth Warren endorses Hillary Clinton

Democratic U.S. Senator Elizabeth Warren threw her support behind Democratic presidential nominee Hillary Clinton Thursday after giving a speech eviscerating Clinton's opponent, Republican nominee Donald Trump.

"I'm going to do everything I can to help Hillary Clinton get elected and I'm going to do everything I can to make sure Donald Trump never comes within shouting distance of the White House," Warren said on The Rachel Maddow Show on MSNBC.

The Nov. 8 election will pit "a tough woman who is willing to lead against a small, insecure bully," she said.

Warren's endorsement comes the same day U.S. President Barack Obama formally endorsed his former secretary of state's bidto succeed him and urged Democrats to line up behind her.

• Barack Obama endorses Hillary Clinton for Democratic nomination

The Massachusetts senator, a fiery critic of Wall Street, is also a favourite among liberals as a possible running mate for Clinton, but speaking to Maddow, she was cagey about the prospect.

Earlier in the evening, Warren spoke at the American Constitution Society, where she went on an all-out attack against Trump, whom she called a "thin-skinned racist bully."

Trump "has never risked anything for anyone and serves no one but himself," she said. "And that is just one of the many reasons why he will never be president."

Warren lambasted Trump for his claims that U.S. District Judge Gonzalo Curiel can't preside fairly over a fraud case involving Trump University because the U.S.-born Curiel is of Mexican descent and Trump wants to build a wall along the border with Mexico.

"You, Donald Trump, are a total disgrace," she said.

"Donald, you should be ashamed of yourself, ashamed for using the megaphone of a presidential campaign to attack a judge's character and integrity because you think you have some God-given right to steal people's money and get away with it. You shame yourself and you shame this country."

• Republicans denounce Trump's 'racist' comments, but stand by their man

The speech was just the latest in Warren's war of words with Trump.

Trump has labelled her "Goofy Elizabeth Warren" and questioned her claim to Native American heritage.

He tweeted last month:

Warren has repeatedly called Trump a "loser."