The Democrat who lost to unknown candidate Alvin Greene in last week's South Carolina Senate primary is formally challenging the results of the race.

Charleston City Councilman Vic Rawl said the "strange circumstances" surrounding the primary vote prompted the challenge. Greene, who didn't spend any money on the campaign besides his filing fee and had no campaign website, won the nomination by 18 points.

The state Democratic party's 92-member executive board will meet on Thursday to hear arguments and decide whether to throw out the results, according to reports.

If the state party decides against Rawl, he could take his case all the way to the state Supreme Court. If they decide for him, Greene could file a formal protest of his own.

Rep. James Clyburn (D-S.C.) said this weekend that the Democratic primary reeked of "elephant dung."

Clyburn charged last week that Greene was likely a "plant" in the race. "I never said he was a Republican plant," he said Sunday on CNN's "State of the Union" program. "I said he was someone's plant. And it turned up after the elections, we found out, as I said earlier, something untoward was going on."

"I saw the patterns in this," Clyburn said. "I know a Democratic pattern, I know a Republican pattern, and I saw in the Democratic primary elephant dung all over the place."

Greene also came to national attention because he was arrested in November and charged with showing obscene photos to a University of South Carolina student. He has not been indicted and declined to comment on the charges when asked about them by The Hill.

Party officials asked Greene to drop out of the race last week after reports of the felony charge emerged.

Sen. Jim DeMint (R-S.C.) is expected to keep his seat.