Former Rhode Island governor Lincoln Chafee (D).
Watch this video to see what you need to know about Chafee in 30 seconds or less.
Chafee first came to Washington as a Republican senator from Rhode Island, appointed to take the seat of his father, John Chafee, when he died. He officially left the Republican party in 2007 after losing a bid for reelection to the Senate. As an independent, he was elected governor of Rhode Island in 2010. Three years later, he joined the Democratic party.
In the past 90 days, Americans have searched for Chafee on the Internet a little more than half as much as they have former Virginia senator Jim Webb. That said, search interest in Sanders and Clinton respectively still dwarfs interest in Webb and Chafee.