This was news to me.
Apparently it was a surprise to Paul Clark as well. He just found out.
But here’s the applicable section from the Delaware Code (Title 9, § 1114):
§ 1114. Vacancy in office.
Whenever a vacancy occurs in the office of County Executive by reason of death, resignation, removal from office or other cause, the President of the County Council shall serve as County Executive until the latter office is filled as a result of an election. If a vacancy in the office of County Executive occurs more than 30 days prior to the date of a primary election in which county officers are nominated, the vacancy shall be filled for the remainder of the term in the next succeeding general election and the County Executive elected in this manner shall take office on the first Tuesday following such election. If a vacancy in the office of County Executive occurs less than 30 days prior to the date of a primary election in which county officers are nominated, the vacancy shall be filled for the remainder of the term by the President of the County Council. If the President of the County Council becomes County Executive, the President’s office as an elected official of the county governing body shall become vacant.
Guess we’d better keep a close eye on Clark to make sure that his limited window runs out with a minimum of chicanery.
Sorry for the short piece. Gotta go to work.