MacKay was inducted into the University of Florida Hall of Fame (the most prestigious honor a student can receive from UF) and was a member of The Board.

In 1988 he received the Democratic nomination for the United States Senate, but lost in a very close race for that office to Connie Mack III.

"[6] In 1998, MacKay sought to succeed the term-limited Chiles as governor, easily winning the Democratic nomination with his full support.

When they returned to their hotel room, they found a message about Chiles' death, asking MacKay to get on a plane to Atlanta, where they were picked up by a state crew and flown through thick fog to Tallahassee.

"There's no great pleasure in this," said MacKay about taking a job he had sought, but got for a short time after his political partner's death.

[4] Despite keeping a low public profile during his time as governor, MacKay made at least 56 appointments to various boards and to various offices, including two judgeships.

He granted six pardons to female prisoners and was involved in such issues as the negotiation plan for the Everglades, and moderated some other disputes.

During his tenure he traveled to 26 countries in the Americas, working on issues such as the Free Trade Area of the Americas (FTAA), the North American Free Trade Agreement (NAFTA), the Caribbean Basin Initiative (CBI), hemispheric security, strengthening the rule of law, labor standards, environmental policies and human rights.