Just a few months ago‚ it was hard to see the ingredients of a Joe Biden comeback—even while squinting at the recipe. The president began the election year with his approval rating at historic lows. He was trailing Donald Trump in almost all of the key battleground states‚ as well as in national polling averages. Influential liberals were so concerned that the octogenarian incumbent did not have another campaign in him that some were openly calling for him to be replaced as the nominee....