Sen. Elizabeth Warren (D-Mass.) speaks on Capitol Hill in November 2015. She has attacked GOP presidential front-runner Donald Trump, calling him “a loser.” (Jacquelyn Martin/AP)

Sen. Elizabeth Warren ­(D-Mass.), who has resisted entreaties by liberals to run for president and who has largely stayed on the sidelines in the race, stepped into the fray Monday with a series of social-media posts attacking Republican front-runner Donald Trump as “a loser.”

In taking on Trump, Warren employed the same tactic that he has often used to great effect: name-calling on social media.

“Many of history’s worst authoritarians started out as losers — and Trump is a serious threat,” Warren added in a Facebook post that within three hours had been shared nearly 51,000 times and had received more than 154,000 “likes.”

She also fired eight tweets in rapid succession. They listed his business failures, and one read: “@RealDonaldTrump knows he’s a loser. His insecurities are on parade: petty bullying, attacks on women, cheap racism, flagrant narcissism.”

The barrage represented a sharp escalation by Warren, who is one of the most influential figures on the Democratic left. At the same time, she seems in no hurry to abandon her neutral stance in her party’s presidential primary, which is notable given that every one of the 13 other female senators is backing former secretary of state Hillary Clinton.

Sen. Elizabeth Warren takes a photo with wellwishers following a news conference with Senate Democrats. (Saul Loeb/AFP/Getty Images)

Warren’s postings came a day after the New York Times published a column by Maureen Dowd in which the billionaire real estate mogul mocked Warren with references to a controversy about her claims to Native American ancestry that had dogged her during her 2012 Senate campaign.

“I think it’s wonderful because the Indians can now partake in the future of the country,” Trump told Dowd. “She’s got about as much Indian blood as I have. Her whole life was based on a fraud. She got into Harvard and all that because she said she was a minority.”

Asked at a Washington news conference Monday about Warren’s attack, Trump responded: “Who is that, the Indian? You mean the Indian?”

Although Clinton is widening her lead over Sen. Bernie Sanders of Vermont, Warren has indicated that she is in no hurry to see the Democratic contest come to an end. “The way I think of it, I’ve been cheering them on, because I’m really proud to be a Democrat, and this primary has made me even prouder,” Warren said last week on MSNBC.

“I gotta tell you, it makes clear the difference between Democrats and, boy, that show that’s going on over on the Republican side,” Warren added. “So right now, I tell you what my timeline is, I like what we’re doing on the Democratic side, and I think it’s what we ought to be doing.”

There is little upside for Warren to wade into the Democratic race, given that Clinton holds a commanding position, while many of Warren’s supporters align with Sanders on most issues.

Republican presidential candidate Donald Trump walks out after speaking Monday at a news conference in downtown Washington at the Old Post Office Pavilion, soon to be a Trump International Hotel. (Jabin Botsford/The Washington Post)

At the same time, she has close ties to several of Clinton’s top advisers. Political consultant Mandy Grunwald, who been a leading strategist for all of Clinton’s campaigns, played a similar role in Warren’s 2012 Senate race. Warren has also been an ally of Gary Gens­ler, the former Commodity Futures Trading Commission head who is the Clinton campaign’s chief financial officer. Brady Williamson, an adviser to Clinton’s campaign, worked with Warren in the 1990s on an effort to overhaul the bankruptcy laws.

Sanders’s presence in the race has also put pressure on Clinton to move toward his — and Warren’s — views on a number of issues. One of them is trade.

In October, Clinton came out against President Obama in his efforts to push through the ­12-nation Trans-Pacific Partnership deal, which she had praised when she was secretary of state. Clinton has also sounded a tougher note on Wall Street, which is a regular target of Warren and Sanders.

Warren has often decried what she says was an overly close relationship between the banking industry and the administrations of Obama and former president Bill Clinton. She has noted, for example, that three of the last four Treasury secretaries appointed by Democratic presidents had “close ties” to Citigroup.

In August, under pressure from liberal groups, Clinton announced her support for legislation, authored by Sen. Tammy Baldwin (D-Wis.), that aims to slow what Warren has described as a “revolving door” between Wall Street and Washington. The measure would prevent financial industry executives from receiving accelerated payouts of restricted stock options and other forms of lump-sum payment if they leave those jobs to take posts in the federal government.

However, the legislation has little chance of passing before the next president takes office, and Clinton has not said whether she would impose a similar restriction on those she would recruit for high posts in her administration, if she is elected.

“Hillary Clinton strongly supports Senator Baldwin’s legislation, and is willing to explore other steps that might help end the revolving door between government and financial institutions,” Clinton spokesman Brian Fallon said Monday.