[National Review] The polls may look great right now for Hillary Clinton, but a deepening criminal investigation into her use of a private e-mail system while she was secretary of state underscores how fragile her lead really is.On Thursday, Fox News reported that multiple intelligence sources claim the FBI has broadened its probe into the former secretary of state's potentially negligent handling of classified information. The nation's top law-enforcement agency is now also investigating whether Clinton or her surrogates made "materially false" statements to federal officials regarding her private e-mail system.