As the selection of Delaware’s next chief justice approaches, a political action committee with ties to one of the most vexing business disputes in the recent history of the state has taken aim at the top judge of the Delaware Court of Chancery Court in a bid to keep him off the high court.

Citizens for a Pro-Business Delaware, in an ad that aired at the end of last week’s Democratic presidential debate, attacked Chancellor Andre G. Bouchard as a member of the court’s “old boy’s club,” an exclusive group of rich, white and mostly male attorneys that the group says is not representative of Delaware’s wider population.