On April 7, 2017, less than four years ago, a majority of Democrats in the U.S. Senate joined a majority of Republicans to sign a letter supporting the filibuster. The letter, to Senate leaders Mitch McConnell and Charles Schumer, began: “We are writing to urge you to support our efforts to preserve existing rules, practices and traditions as they pertain to the right of members to engage in extended debate on legislation before the United States Senate.”