Tuesday’s election result trend lines were a political nightmare for the Democratic Party, and no Democrat who cares about winning elections in 2022 and the presidential race in 2024 should see them as anything less. Familiar takeaways like “wake-up call” and “warning shot” don’t do justice here because the danger of ignoring those trends is too great. What would do justice, and what is badly needed, is an honest conversation in the Democratic Party about how to return to the moderate policies and values that fueled the blue-wave victories in 2018 and won Joe Biden the presidency in 2020. Given...