Mr. Robinson, the Republican nominee for governor of North Carolina, vowed to stay in the race and sought to deny the report, which also said he had defended slavery in online posts years ago.

Republican North Carolina gubernatorial candidate Mark Robinson referred to himself as a “Black Nazi,” disparaged Martin Luther King Jr., used antisemitic and homophobic slurs and spoke highly of slavery on a pornographic website before his entrance into politics, according to a new CNN report —as Robinson denies making the comments.