What a difference a year makes. Last spring, Speaker Nancy Pelosi sounded an alarm of caution over a hyper-partisan impeachment. In the fall, she flipped her position to go all-in on an impeachment scenario that would pass the House with bipartisan opposition. Her gleeful distribution of ceremonial pens heralded the cementing of a historical asterisk next to the presidency of Donald J. Trump. It was the culmination of a three-year spaghetti-throwing operation undertaken by Democrats to weaken the president and the Republican Party, if not overturn the 2016 election. As the afterglow of her impeachment vote victory fades into history,...