Politico: The Delaware Democrat obviously supports Sen. Barbara Boxer (D-Calif.) in her heated campaign for a fourth term this November. But he also stands to win big if she loses. Carper is next in line to snag Boxer’s spot as the party’s leader on the Environment and Public Works Committee, a panel polarized by politics and dysfunction since the mid-1990s. And while Carper refuses to discuss the scenario — he’s banned his staff from talking about it publicly — the prospect of a …