Maine Democrats are picking a new Senate nominee to replace Graham Platner through a delegate process that grassroots supporters see as an establishment power grab.

• Platner won a record number of votes on an anti-war, populist message, but is stepping aside after damaging allegations surfaced.
• The state party will let about 600 delegates choose the replacement, including 100 party insiders acting as superdelegates — a setup many call undemocratic.
• Top contenders are Troy Jackson, a pro-labor logger backed by Bernie Sanders who opposes military aid to Israel, and Nirav Shah, a popular former public-health official now dogged by a deadly outbreak on his watch.
• Senator Tammy Duckworth publicly warned against sending Shah to the Senate, which could sink his chances.
• Many Platner voters feel cheated by the timing and may not turn out, which would hurt Democrats in a close race against Susan Collins.

Outlook: County caucuses over the next week will pick delegates, but disillusioned grassroots activists could tank turnout no matter who wins the nomination.