Complex sentence: Bridget takes Fievel and Tony to Honest John, an alcoholic but reliable politician who knows all the voting mice in New York City; but because the Mousekewitzes have not yet registered to vote, he cannot find them.
Split into simpler sentences: Bridget takes Fievel and Tony to see Honest John, a drunk but reliable politician who knows all the voting mice in New York City. But, as the Mousekewitzes have not yet registered to vote, he cannot help Fievel find them.