For nearly as long as FBI special counsel Robert Mueller has been investigating Russian election meddling, activists have been planning mass protests. Hundreds of protests across the US, organized by MoveOn and other progressive groups, are planned to begin if Trump fires Mueller or deputy attorney general Rod Rosenstein, who appointed him. They would also begin if the president prevents the investigation from being “conducted freely,” MoveOn says. Today, those fears may have been realized when Trump asked attorney general Jeff Sessions for his resignation. Sessions, who had recused himself from the investigation, will be replaced by Matt Whitaker, a...