An early resignation by Sen. Thad Cochran, R-Miss., for health reasons, something aides and allies insist is not imminent, could set up another front in the civil war that threatens to roil Republican primaries in 2018.

Insurgents preparing to challenge Sen. Roger Wicker, R-Miss., next year are now eyeing the special election that would be called if Cochran stepped down. It’s a concern for a Republican establishment faced with diverting resources from the general election to quash a rebellion initiated by Steve Bannon, President Trump’s former chief strategist.