Greene was considered such a long shot that his opponent and media didn't even bother to check his background. If they had, they would have discovered he faces a felony obscenity charge after an alleged encounter with a college student last fall.
After The Associated Press reported Greene's charge Wednesday, the leader of the state Democratic party said she asked Greene to withdraw from the race.
"I did not do this lightly, as I believe strongly that the Democratic voters of this state have the right to select our nominee," Fowler said. "But this new information about Mr. Greene ... would certainly have affected the decisions of many of those voters."
But Greene said he will not step aside.
"The Democratic Party has chosen their nominee, and we have to stand behind their choice," Greene told the AP at his home in Manning. "The people have spoken. We need to be pro-South Carolina, not anti-Greene."
Court records show Greene was arrested in November and charged with showing obscene Internet photos to a University of South Carolina student, then talking about going to her room at a university dorm.
Charged with disseminating, procuring or promoting obscenity, Greene could face up to five years in prison. He has yet to enter a plea or be indicted.
South Carolina state law prohibits convicted felons from serving in state office. Felons can serve in federal office, although the U.S. House or Senate could vote to expel any member deemed unfit to serve.
Rawl said he didn't know about Greene's arrest until reading media reports about it.
"It's an absolute surprise," Rawl said. "I can't really make any comments, because I don't know what's going on."
Greene welcomed a reporter into his childhood home he shares with his father Wednesday afternoon along the backroads to Myrtle Beach. Wearing warmup pants and a green family reunion shirt from 1993, he had to be repeatedly cajoled to get his picture taken.
He seemed overwhelmed by his new fame and admitted he has no campaign signs, staff, buttons or even a slogan. He hoped the state and national party leaders might call him back, this time to offer some help.
"I need my state and national party to help me," Greene said. "See, I don't have any signs. Those take campaign contributions."
He declined to comment about his pending felony charge, but the college student he was accused of approaching described the incident to the AP. It's not clear what Greene was doing on the campus.
Camille McCoy, a 19-year-old rising sophomore at the University of South Carolina, said she called campus police after Greene sat down next to her in a computer lab and asked her to look at his screen, which showed a pornographic website.
"I said, 'That's offensive,' and he sat there laughing," said McCoy, who was 18 at the time. "It was very disgusting. He said, 'Let's go to your room now.' It was kind of scary. He's a pretty big boy. He could've overpowered me."
McCoy, who is from Charleston, said she was stunned to learn that the same man she later identified from a photo lineup was running for office, much less had won a party's nomination.
"You're kidding?" said McCoy, who is a Republican. "Oh my gosh, that's ridiculous!"
Meanwhile, questions abounded in the day-after deconstruction of Greene's win.
Had Rawl been a victim of the anti-incumbent sentiment that swept the state's primaries? He only carried four counties, but one was Charleston, where he currently serves on county council.
Did Greene capitalize on some sort of a movement among either black voters or the unemployed? A subset of the Machinists' union ran cable ads in South Carolina encouraging the state's jobless to vote, but the group says it never promoted Greene or mentioned his name. The director of the state's NAACP chapter says he knew nothing about Greene, who is black, before the win.
It might come down to the simple fact that his name was listed before Rawl's on the alphabetized ballot, a possibility Fowler said she pondered Tuesday night.
Even if Rawl had been successful, one analyst was skeptical it would have made a difference against DeMint, a tea party darling who has marshaled a $3.5 million war chest to win his second term.
"A lot of it speaks to the lack of depth of the bench for the Democratic Party in South Carolina right now," said Scott Huffmon, a political scientist at Winthrop University. "Their best shot in November, really, is the Governor's Mansion."
Associated Press Writers Seanna Adcox in Columbia, Jeffrey Collins in Manning and researcher Barbara Sambriski in New York contributed to this report.