On the campaign trail, Hillary Clinton has been pushing hard to overhaul of the country's broken campaign finance system. "We need to fix our dysfunctional political system and get unaccounted money out of it, once and for all, even if that takes a constitutional amendment," Clinton said during one of her first official speeches in Iowa last month. Clinton's campaign finance rhetoric appears to be aimed at super-PACs, the quasi-independent organizations that bolster campaigns by buying ads. But when it comes to the major funders behind her own presidential campaign, the Democratic front-runner has yet to answer questions about how...