Hillary Clinton met with Senator Elizabeth Warren Friday, fueling speculation that Clinton talked to Warren about being a possible running mate. It would be a dream ticket for liberal Democrats. Warren endorsed Clinton Thursday night, but she hasn’t always been such an ardent supporter of her. In fact, in her 2003 book, The Two-Income Trap, Warren suggested that Clinton wasn’t a very principled politician, and that she bowed to Wall Street pressure in a controversial vote she cast on a bankruptcy bill in 2001.