Update: National Review editor Rich Lowry sent the following statement:
"Sorry, Grover. But our extensive market research shows that partially obscured bearded anti-tax activists do very poorly on our covers. In addition to a partial Grover head, we removed a detached arm and a few other random heads from the image to make it more visually clean and to focus on the politicians in the foreground. The table of contents of the issue contains this disclaimer: 'The cover image was altered slightly, to remove people standing in the background.'"
McKay Coppins is a senior writer for the BuzzFeed News politics team, and the author of The Wilderness, about the battle over the future of the Republican Party.