For the Democratic Party, the road to Maine’s Senate primary is paved in dread. Subscribe to read this story ad-free Get unlimited access to ad-free articles and exclusive content.All Graham Platner had to do was glide into Tuesday’s election to clinch the state’s Democratic Senate nomination, since Gov. Janet Mills abruptly suspended her campaign in late April. But with each passing day, the divisions inside the party have grown as some lawmakers and activists say they are increasingly alarmed over the breadth and depth of controversies and scandals facing the military veteran. As some Democrats nervously wondered what the next...