In this photo taken May 20, 2015, Democratic Presidential candidate Sen. Bernie Sanders, I-Vt., poses for a portrait before an interview with The Associated Press in Washington. For Democrats who had hoped to lure Massachusetts Sen. Elizabeth Warren into a presidential campaign, independent Sen. Bernie Sanders might be the next best thing. Sanders, who is opening his official presidential campaign Tuesday in Burlington, Vermont, aims to ignite a grassroots fire among left-leaning Democrats wary of Hillary Rodham Clinton. He is laying out an agenda in step with the party's progressive wing and compatible with Warren's platform _ reining in Wall Street banks, tackling college debt and creating a government-financed infrastructure jobs program. (AP Photo/Jacquelyn Martin)