Sen. Elizabeth Warren published a strong attack on Donald Trump on Monday, in which she called the Republican presidential frontrunner a uniquely dangerous threat to America.

"More than anyone we’ve seen before come within reach of the presidency, Donald Trump stands ready to tear apart an America that was built on values like decency, community, and concern for our neighbors," wrote Warren, a Massachusetts senator who enjoys broad support among liberals.

Warren's rebuke, posted on her Facebook page, emphasized the importance of the general election for several important public policy issues like health care, Social Security, and Wall Street reform.

But Warren also criticized Trump for being a "loser," taunting him for his "failed businesses" and accusing him of being "so bad at business."

"Trump seems to know he's a loser," she said. "His embarrassing insecurities are on parade: petty bullying, attacks on women, cheap racism, and flagrant narcissism."

Warren, a former Harvard law professor, added that Trump's status as a "loser" mirrors the beginnings of authoritarians throughout history.

"Many of history’s worst authoritarians started out as losers — and Trump is a serious threat," she said. "The way I see it, it’s our job to make sure he ends this campaign every bit the loser that he started it."

Let’s be honest – Donald Trump is a loser. Count all his failed businesses. See how he kept his father’s empire afloat... Posted by Elizabeth Warren on Monday, March 21, 2016

Trump appeared to fire back at Warren Monday afternoon: