Massachusetts Sen. Elizabeth Warren ended her bid for the presidency on Thursday, marking the end of a campaign that once rocketed Warren to front runner-status. In her exit speech, Warren acknowledged "all those little girls who are gonna have to wait four more years" for a woman to have a shot at the presidency. Her exit raises questions about why, with a historic number of women running for president, the only seemingly viable candidates remaining are white men.This episode: White House correspondent Tamara Keith, political reporter Danielle Kurtzleben, and national political correspondent Mara Liasson.