Hemingway was never terribly “active” politically, but he did voice his opinion on things of a political nature (mostly the things he found objectionable). Try to get you hands on any of the following:Ernest Hemingway on Writing edited by Larry W. Phillips. There is a short chapter here titled “Politics,” which contains Hemingway’s interesting reflections on the political life.Hemingway’s 1937 speech to the American Writers’ Congress demonstrates his willingness to speak up against oppressive systems of government. The speech is titled “Fascism is a Lie” and is reprinted in Conversations with Ernest Hemingway edited by Matthew J. Bruccoli, pages 193-195.Hemingway’s 1940 novel, For Whom the Bell Tolls shows his concern with the Spanish Civil War and political overtones are present throughout the narrative and dialogue.Keneth Kinnamon’s essay, “Hemingway and Politics” in The Cambridge Companion to Ernest Hemingway edited by Scott Donaldson may also be of interest.