As Trump barrels forward, Democrats are engaged in a furious argument over how to stop him. Many Democratic primary voters indicate they are ready to support the candidate most likely to defeat Trump, even over their personal favorite. Joe Biden has become the early front-runner because of a widespread sense that he is the “safest bet” to defeat Trump. Experienced and moderate, “Scranton Joe” is credited with having a special appeal to the white working-class voters that went to Trump, particularly in the In fact, rather than the “safest bet,” Biden is more likely to end up the worst of...