Bangor, Maine —

Maine Democrats are poised to pick Troy Jackson as their new Senate nominee on Saturday, the culmination of a brief and unusual contest to replace Graham Platner after he left the battleground race amid scandal.

Organizers of the party convention had envisioned a robust field of candidates vying to win a majority of 601 delegates picked from across the state. Instead, Jackson, the former Maine Senate president who lost a bid for governor earlier this year, filled most delegate slots with his supporters and forced his most serious opponents to drop out. He has one opponent left: Saundra Pelletier, a political unknown.

“I don’t think anybody saw it coming,” said Dan Kleban, who was among the candidates to enter the field after Platner’s withdrawal only to step aside for Jackson. “I know there are people who might be a little bitter about the process or the way Troy played it, but we’re going to need someone who can put together that kind of sophisticated organization and Troy showed he could do that.”

Jackson’s expected nomination will wrap up a tortuous journey by Maine Democrats to find a candidate for one of the most consequential races in this year’s battle for control of the US Senate.