Senator Kamala Harris
Sen. Harris has taken a “Never Trump” stance on his nominations for cabinet positions and the Supreme Court. On policy she opposes Trump on immigration, taxes, healthcare and guns. Some of her rhetoric, however, has been over the top, such as at least referencing and thus promoting a comparison between ICE and the Ku Klux Klan. She also attempted to apply an anti-Catholic religious test to a judicial nominee because he belonged to the Knights of Columbus. Like most of the other candidates she is moving toward the far left. In a general election it would again be a battle between red states and blue states.
Wikipedia article on Sen. Kamala Harris
LA Times -- Kamala Harris makes it official: She’s running for president
Wikipedia -- The 2008 Democratic Primary
WSJ -- The Making of Kamala Harris