Sen. Elizabeth Warren endorsed presumptive Democratic nominee Hillary Clinton on Thursday night, delivering key progressive backing at a time when Clinton is working to unify the party.
"I am ready to get into this fight and work my heart out for Hillary Clinton to be the next president of the United States and make sure that Donald Trump never gets anywhere near the White House," Warren said on the Rachel Maddow Show on MSNBC.
The Massachusetts senator was the only Democratic woman in the Senate who is not yet supporting Clinton. A progressive firebrand, Warren is in many ways more politically aligned with Clinton's chief rival, Vermont Sen. Bernie Sanders.
At the same time, Warren's name has been mentioned repeatedly as a possible vice presidential choice who could help Clinton appeal to the party's more liberal wing.
In her interview with Maddow, Warren acknowledged her respect for Sanders and the issues that have animated his campaign, including income equality and Wall Street greed. But she said the threat of Trump becoming president motivated her to support Clinton, whom she called "a fighter."
"As a Democrat, one of things that frustrates me is that we just don't get into the fight...," Warren said. "You have to be willing to throw a punch."
She said she had not spoken to Clinton about the vice president's position and was happy with her work in the Senate. Asked if she believed she was capable of filling the No. 2 slot, Warren said "Yes, I do."
Warren has become increasingly vocal in her criticism of presumptive GOP nominee Donald Trump. In a speech Thursday night she called Trump a "loud, nasty, thin-skinned fraud."
Warren's endorsement came hours after President Barack Obama met with Sanders , then announced his own endorsement of Clinton . Vice President Joseph Biden added his endorsement during a speech in the evening.
The Republican National Committee called Warren a "sellout," given her policy differences with Clinton.
“Whether it’s the Wall Street speech transcripts she refuses to release, her ties to the fossil fuel industry, or coziness with big banks, Hillary Clinton represents everything Elizabeth Warren supposedly stands against,” RNC spokeswoman Lindsay Walters said in a statement .
In her speech before the American Constitution Society on Thursday evening, Warren lashed out at Trump, particularly about his namesake Trump University.
"I taught law for more than 30 years. Ask any lawyer in America and they’ll tell you that sounds like fraud," Warren said in a speech prepared for the "And that’s exactly what Donald Trump is being sued for – fraud, and worse, for targeting the most vulnerable people he could find, lying to them, taking all their money and leaving them in debt."
Warren said that Trump was operating as though the rules do not apply to him in "race baiting a judge" involved in the case, who is American-born of Mexican heritage.
"So at a political rally two weeks ago, and almost daily since then, the presumptive Republican nominee for president of the United States has savagely attacked Gonzalo Curiel, the federal judge presiding over his case," Warren said.
Speaking to the liberal legal audience, Warren said one of the results of the judicial confirmation process under the Republicans more generally has been to affect the kind of legal background that an individual needs to be confirmed as a federal judge.
"The goal is to tilt the game, and it’s working – 86% of President Obama’s judicial nominees have worked as a corporate attorney, a prosecutor, or both, while less than 4 percent have worked as lawyers at public interest organizations," Warren said. "Professional diversity is missing from the federal bench – and justice suffers for it."
A spokesman from Senate Majority Leader Mitch McConnell, R-Ky., said Warren does not have credibility in discussing federal confirmations.
"If Sen. Warren held her current beliefs about ensuring votes for all nominees when her party was engaged in serial and unprecedented filibusters against women and minorities during the Bush administration, she kept them to herself," said McConnell spokesman David Popp.
Warren also brought up McConnell in Thursday's speech, particularly his refusal to consider Obama's nominee for the Supreme Court, Judge Merrick Garland of the DC Circuit Court of Appeals.
"Trump isn’t a different kind of candidate," Warren said. "He’s a Mitch McConnell kind of candidate. Exactly the kind of candidate you’d expect from a Republican Party whose 'script' for several years has been to execute a full-scale assault on the integrity of our courts.
"Blockading judicial appointments so Donald Trump can fill them, smearing and intimidating nominees who do not pledge allegiance to the financial interests of the rich and the powerful."