So, U.S. Senate Republicans are fighting campaign-finance legislation that would disclose the identities of corporate donors. It's one thing to argue that the First Amendment entitles businesses to influence American elections. It's beyond any reasonable logic, however, to demand that corporations should be able to do so anonymously. Laws governing political advertising have required for decades that the organizations producing the ads must identify themselves. I ask Senate Minority Leader Mitch McConnell, R.-Ky., who is planning to lead his party in a filibuster against the legislation: Why is it important for you to conceal the sources of the millions of dollars that will be flowing into campaigns from the richest institutions on the planet?JEFF NAYLOR, MINNEAPOLIS