Rep. Ryan Winkler, a Democrat who sits in the Minnesota House, sent the tweet after learning of the 5-4 Supreme Court decision that southern states cannot be required by the Voting Rights Act to get pre-clearance for changes in election procedures, the Minneapolis Star Tribune reported.
"VRA majority is four accomplices to race discrimination and one Uncle Thomas," Winkler said.
Winkler later apologized for the message. He also said he had decided against running for secretary of state, although he said that decision was made before the "Uncle Thomas" debacle.
In his apology, Winkler described the Voting Rights Act as one of the most important measures in U.S. history to end racial discrimination. He said he was disappointed by the court ruling.
"In expressing that disappointment on twitter, I hastily used a loaded term that is offensive to many," he added. "My words were inappropriate and I apologize."