Sen. Elizabeth Warren Elizabeth WarrenBiden's fiscal program: What is the likely market impact? Warren, Schumer introduce plan for next president to cancel ,000 in student debt The Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon MORE (D-Mass.) is stepping into the ring against Donald Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE, labeling the Republican presidential contender a “loser” who plays on “cheap racism” for votes.

The aggressive broadsides, delivered Monday via Twitter, marked a new level of involvement in the 2016 race for Warren, a liberal hero who rejected efforts to draft her into the contest last year.

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Warren has refused to make an endorsement for the Democratic nomination despite pressure from women in the Senate to back Hillary Clinton Hillary Diane Rodham ClintonWhat Senate Republicans have said about election-year Supreme Court vacancies Bipartisan praise pours in after Ginsburg's death Trump carries on with rally, unaware of Ginsburg's death MORE over Sen. Bernie Sanders Bernie SandersKenosha will be a good bellwether in 2020 Biden's fiscal program: What is the likely market impact? McConnell accuses Democrats of sowing division by 'downplaying progress' on election security MORE (I-Vt.). While she has thus far resisted that pressure, Warren appears ready to come off the sidelines for the general election.

She used her social media perch to lob insult after insult at Trump on Monday, painting the real estate mogul as a failure in business and calling him a “loser” five times across eight tweets.

“@RealDonaldTrump knows he’s a loser. His insecurities are on parade: petty bullying, attacks on women, cheap racism, flagrant narcissism,” read one message from Warren’s campaign Twitter account.

When asked about Warren’s criticisms Monday, Trump jabbed right back.

“The Indian? You mean the Indian?” he responded during a press conference in Washington, alluding to a campaign controversy during Warren’s 2012 Senate run over why she listed herself as Native American during her time at Harvard Law School. Warren said she had learned of some Native American heritage from her family.

The sharp words, and the headlines they produced, indicate Warren could play an outsize role for Democrats this fall, with some even floating the idea of her serving as vice presidential nominee.

Even if she doesn’t end up on the ticket, Democrats are hopeful Warren can be a unifying force. By declining to make an endorsement, they argue, she is uniquely positioned to bridge the gap between the Sanders and Clinton wings of the party.

For now, Warren appears focused on using her influence to batter Trump.

Across Facebook and Twitter, tens of thousands of people saw her shots at the celebrity New Yorker as she adopted the harsh tone she usually reserves for Wall Street and the big banks.

The bombardment came as a surprise; Warren has not been a major critic of Trump during the lengthy GOP primary proscess, and the Twitter account she used to launch the attack had been practically dormant for nearly a month.

“She’s pretty cautious by nature, so I found it interesting that she’s finally decided to go after Trump,” said Jim Manley, a Democratic strategist and former aide to Senate Minority Leader Harry Reid Harry Mason ReidSenate Republicans signal openness to working with Biden Mellman: The likely voter sham Bottom line MORE (D-Nev.) who has endorsed Clinton. “It’s very important for Democrats to start focusing on the real threat, and that’s Donald Trump.”

After the personal and professional insults, Warren ended her social media flurry with a call for unity.

While Warren said some might see Trump as a loser who “kept his father’s empire afloat using strategic corporate bankruptcies to skip out on debt,” she urged her backers to treat him as a “serious threat.”

“Just because Trump is a loser everywhere else doesn’t mean he’ll lose this election. People have been underestimating his campaign for nearly a year — and it’s time to wake up,” she wrote on Facebook. “The way I see it, it’s our job to make sure he ends this campaign every bit the loser that he started it.”

Some on the left have openly grumbled that Warren should have thrown her political weight behind Sanders, given that his anti-Wall Street message is clearly more in line with hers.

But it may be too late for such an endorsement to make a difference; Clinton is pulling away with the delegate count, and appears on track to win the nomination despite Sanders’s vow to fight all the way to the convention.

Warren has offered praise for both Sanders and Clinton during the primary process, particularly when they have called for tougher action against the financial industry.

With Clinton shifting her focus to the general election, Democrats like Warren are beginning to follow suit.

“Attacking Trump is going to be front and center for most Democrats from here on out,” Manley said.

In trying on the mantle of party unifier, Warren got some support from the Democratic front-runner, with Clinton retweeting one of Warren’s Trump attacks from her own account.

Warren returned to social media later in the day for a parting shot, calling Trump a “wannabe tyrant.”

“It’s up to all of us to stop @­realDonaldTrump,” she tweeted.