COLUMBIA -- With South Carolina's sordid history of dirty politics, it's no wonder that conspiracy theories abound about an unknown, unemployed military veteran winning the Democratic nomination for the U.S. Senate.

This is, after all, the birthplace of political maestro Lee Atwater and where rumors of an illegitimate black child ruined John McCain's 2000 presidential run.

Perhaps the most surprising element of Alvin Greene's victory so far is that nothing yet sufficiently explains how it happened.

Greene stunned the state with his win Tuesday over a four-term former lawmaker considered the presumptive Democratic nominee. The 32-year-old candidate who lives with his father and faces a felony charge will challenge Republican juggernaut Sen. Jim DeMint in the fall.

The week has seen Greene change from sweat pants and a T-shirt to dark suit and tie, but he's still fumbling his way through interviews as he did before the election, when he repeated several vague phrases about job creation to an Associated Press reporter and declined to talk about where he campaigned.

"Last weekend, was the first, I mean, I had friends and their friends help," Greene said Wednesday. "I mean, I don't want to talk about the campaign. We get caught up in the campaign -- 'How he won?' -- whatever. I worked hard."

The result stumped Greene's opponent, Vic Rawl, who has accepted the help of a couple of mathematics professors who found some possible anomalies in voting patterns.

Another expert examined voting machines used in the primary to check for malfunctions or tampering. The campaign promised to release any information gathered by the experts and their conclusions.

When The Associated Press broke word of the felony charge on Wednesday, the stunned Democratic establishment lashed out with a panoply of suspicions over how Greene could have paid his $10,440 filing fee and won.

House Majority Whip Jim Clyburn wants authorities to investigate. "Something is amiss," he said.

While it's tough to explain how the unemployed Greene came up with the cash (he said he saved up for two years), the conspiracy theories posed by analysts and Democrats are not ironclad:

--Is Greene a shell candidate who got help from GOP forces seeking to discredit the Democratic Party? Greene said he hasn't had help from anyone, save friends and family. State Republican officials call the allegation "absurd."

--The state has open primaries, which means Republican voters could have chosen to vote in the Democratic primary and gone for Greene. But then crossover voters couldn't have voted in a more-important four-way race for governor on the GOP ballot.

--More than twice as many voters cast ballots in the GOP primary than in the Democratic contest, and vote totals show 19,000 voters selected a Democratic candidate for governor but skipped the U.S. Senate part of the ballot.

--Third-party help? Did Greene, who is black, get help from outside groups? A group that ran cable ads encouraging the unemployed to vote said it never promoted him, and the director of the state's NAACP chapter said he knew nothing about Greene before Tuesday night.