Sen. Elizabeth Warren labeled Donald Trump a loser, a bully and a threat on Monday, continuing a fierce war of words between the liberal icon and the front-running Republican presidential candidate that has played out on social media and The New York Times. “@RealDonaldTrump knows he’s a loser. His insecurities are on parade: petty bullying, attacks on women, cheap racism, flagrant narcissism,” the Massachusetts Democrat wrote on her campaign’s Twitter account on Monday, part of a rapid-fire burst of eight tweets attacking the billionaire television personality. “But just because @realDonaldTrump is a loser everywhere else doesn’t mean he’ll lose this...