Donald Trump early Sunday fired back at Sen. Elizabeth Warren (D-Mass.) after she slammed the presumptive GOP nominee and his vice presidential pick. "Goofy Elizabeth Warren, who may be the least productive Senator in the U.S. Senate, must prove she is not a fraud," Trump tweeted. "Without the con it's over." Donald J. Trump ✔@realDonaldTrump Goofy Elizabeth Warren, who may be the least productive Senator in the U.S. Senate, must prove she is not a fraud. Without the con it's over 11:15 PM - 16 Jul 2016 Donald J. Trump ✔@realDonaldTrump I hope that Crooked Hillary picks Goofy Elizabeth Warren,...