Sanford made the announcement on Fox News Sunday, becoming the third GOP candidate to launch a long-shot bid for the party's nomination.
"I am here to tell you now that I am going to get in," he said.
The announcement came one day after South Carolina's GOP party announced it would not hold primaries in the state, instead offering support to Trump. The move, which the state's GOP party said was unnecessary due to Trump having "no legitimate primary challenger," means Sanford would not be able to win his home state. Kansas has also said it would halt its Republican caucus in the state and other states are expected to follow in canceling GOP contests, including Nevada and Arizona.