Court records show 32-year-old Alvin Greene was arrested in November and charged with showing obscene Internet photos to a University of South Carolina student. The felony charge carries up to five years in prison.
Greene said he had no comment when asked about the charge Wednesday and hung up on a reporter.
The unemployed veteran posted bond after his arrest. He has yet to enter a plea or be indicted.
Records indicate Greene showed photos to a woman and talked about going to her room at a university dorm.
On Tuesday, Greene stunned state Democratic Party leaders by winning the nomination. He raised no money and put up no campaign website. He beat former four-term state lawmaker Vic Rawl, 64, who had raised about $186,000 and had to abruptly scrap a late-week fundraiser for the fall.
Greene said he spent a total of 13 years in the Air Force and Army before leaving the Army in August.
DeMint, a conservative Republican and tea party darling pursuing a second term, has marshaled a $3.5 million war chest already to face the bare-pockets Democratic underdog.
Political analysts don't give Greene a chance. Few expected Rawl would have fared better.
Rawl's lengthy resume lists four past state House terms and former posts as prosecutor, circuit court judge and more.