The cost of preserving and promoting the Hunley submarine has soared to nearly $100 million — thanks largely to a powerful politician’s behind-the-scenes work to steer public money toward his pet project.

The Hunley is one of South Carolina’s biggest financial undertakings in modern times. Not counting university expansion projects, the Hunley ranks behind only a few large road and bridge projects. It even exceeds the $62 million State House renovation in the 1990s.