In September 1998, Greg Craig, a lion of the Washington legal community, left a top job at the State Department to go to the White House to help Bill Clinton fight impeachment during the Monica Lewinsky scandal. One of his first stops was to an old Democratic friend, Sen. Kent Conrad of North Dakota, who warned him what he was stepping into: “You’re about three days away from a delegation of senior Democrats coming up there to ask the president to resign.” That anecdote, recounted in Peter Baker’s history of the impeachment saga, came echoing back to mind in recent...