Donald Trump is actively campaigning to remove Thomas Massie from office during a heated primary contest in Kentucky.The electoral race has emerged as one of the most expensive House campaigns in the US after spending exceeded 32 million dollars.Challenger Ed Gallrein maintains a narrow lead over the incumbent in recent polls as the former president continues his vocal criticism.Voters in the 4th district remain divided between the independent record of the congressman and the nationalist agenda supported by the challenger.