NEW YORK • Republicans spent an entire primary cycle searching for Mr Donald Trump's weak spot, to little avail.
But Ms Elizabeth Warren (photo), a first-term Democratic senator from Massachusetts, seems to have come up with an answer - or at least a way to rattle the New York billionaire.
Last Friday evening, tensions between Mr Trump and Ms Warren spilled over into a Twitter war spanning four hours and more than a dozen posts and insults - "Goofy Elizabeth Warren", he called her; a sexist, racist, xenophobic "bully", she countered - on both sides.
The back-and-forth, which played out in public rat-a-tat-tat bursts, 140 characters at a time, also offered a vivid preview of how the six months until election day could unfurl, with the popular Ms Warren emerging as a unifier of the Democratic base and Mr Trump - so far, at least - still unable to resist small provocations as he tries to become a more disciplined general election candidate.
Ms Warren is one of the few high-profile leaders in either party to repeatedly challenge Mr Trump with clarity and directness, portraying him as both dangerous and a charlatan.
She began her assault in a March 21 Facebook post, describing his candidacy as a "serious threat" and calling him "a loser" - one of the worst insults in the Trump lexicon.
And last Tuesday, the night Mr Trump became the presumptive Republican presidential nominee, she again took to Facebook to denounce him.
Three days later, Mr Trump launched a series of Twitter posts deriding her as "goofy" and as a "flunky" of Democratic front runner Hillary Clinton.
In a dozen Twitter posts last Friday, Ms Warren not only called Mr Trump a bully who can be defeated "not by tucking tail and running, but by holding your ground", but also adopted Mr Trump's Twitter style, writing: " 'Goofy,' @realDonaldTrump? For a guy with 'the best words' that's a pretty lame nickname. Weak!"
Ms Warren appears to take seriously her role in uniting the Democrats. And in an e-mail statement, she cast herself as someone willing to challenge Mr Trump.
"Republicans waited way too long to stand up and tell the truth about Donald Trump's record, his temperament, and why he is unfit to be president," she said. "We can't repeat that mistake."
NEW YORK TIMES