Former Rhode Island governor Lincoln Chafee officially announced Wednesday that he will vie for the Democratic presidential nomination. Chafee, a Republican turned independent turned Democrat, made the announcement during a foreign policy speech at George Mason University. He joins a relatively narrow Democratic field, which so far includes frontrunner Hillary Clinton, Vermont Sen. Bernie Sanders (I), and former Maryland Gov. Martin O'Malley. Chafee's campaign has so far centered around attacking Hillary Clinton's foreign policy record as secretary of state.