In 1954, Collins decided to run for governor. Following the death of Governor Daniel McCarty in 1953, the governorship passed to Senate President Charley Johns on an interim basis. Johns decided to run for election as governor as well, but Collins managed to defeat him in the ensuing Democratic Party primary. Shortly after he assumed office in 1955, the state decided to construct the new Governor's Mansion on the site of the previous one. It was at this time that The Grove functioned as the de facto Governor's Mansion, a role it fulfilled until the completion of the new building in 1957. Collins was the first governor to live in the new mansion. Mary Call Darby Collins was actively involved in selecting the furnishings of the new mansion. James Cogar, who worked at Colonial Williamsburg, worked with Mrs. Collins on the mansion furnishing plan and after they finished, she hired Cogar to help open The Grove as a public museum. When the Collins family took possession of The Grove in the early 1940s, most of its original furnishings were gone, sold by either Ellen Call Long or Reinette Long Hunt to help make ends meet. It was largely through the efforts of Cogar that the Collins family acquired most of the period pieces used to furnish the house.