(CNN) – A prominent conservative is issuing an ultimatum, essentially telling the candidate he supports to do better in the polls – or lose his support. Erick Erickson, editor-in-chief of RedState.com, backs Assemblyman Chuck DeVore in the California Republican senate primary. DeVore is locked in a battle with former Hewlett-Packard CEO Carly Fiorina and former Rep. Tom Campbell for the right to face Democratic Sen. Barbara Boxer in November. Speaking Tuesday with CNN Chief National Correspondent John King, Erickson – a CNN contributor - said he won't support DeVore much longer if the candidate does not improve his political standing....