A new poll from over the weekend in Iowa has Biden leading with 24 percent, followed by Sanders (16), Warren (15), Buttigieg (14), Harris (7), and everyone else. If this was the Iowa polling 10 days before the caucuses, you’d say that Biden was in pretty good shape, but by no means a guaranteed winner given how fast Iowa can shift (certainly if someone else had momentum). Eight months before the caucuses is a very long time to try to protect an 8-point lead. Also, Biden supporters aren’t very enthusiastic and he’s doing best among Democrats who say they plan to caucus virtually (in a new arrangement, people can literally phone it in, but they will only decide 10 percent of the delegates). In short, Biden is indisputably the front-runner, but hardly looks impregnable.