Alvin Greene's shock victory in the Democrat primary for South Carolina's senate seat has left both the state's political establishment and pundits at a loss. The 32-year-old "mystery man" who'll face Republican senator Jim DeMint in November is an unemployed Army veteran who attended no campaign events, bought no advertising and — unthinkable in 2010 — did not even have a campaign website. What's more, it's emerged that Greene is facing felony charges for allegedly showing lewd photos to a University of South Carolina student. How did this happen? (Watch Alvin Greene say he has a shot to win)

1. "Hard work"
Greene told Suzy Khimm at Mother Jones that his victory was the result of "hard work, and just getting my message to supporters." Yet in a "rambling" three-hour interview with Manuel Roig-Franzia at The Washington Post, the candidate reportedly "could not name a single specific thing he'd done to campaign for lofty political office." Greene maintains that details of how he won are not relevant. "I'm not concentrating on how I was elected — it's history," he told Khimm. "We need to get talking about America."

2. An alphabetical fluke
State Democratic Party chair Carol Fowler has offered the "uber-scientific" suggestion, says Haley Cohen at Vanity Fair, that Greene won because his name appeared first on the ballot paper, ahead of rival Vic Rawl, a four-term state lawmaker. "This theory may also account for how Bush won twice," quips Cohen.

3. He's a GOP plant
Some suspect Greene's "curious candidacy" may not be all that it seems, says Corey Hutchins at the Columbia Free Times. "Republican place markers" — that is, deliberately weak candidates funded by the GOP — are "campaign legend" in South Carolina. In the early 90s, an unemployed black fisherman was "coaxed" into running in a primary race to increase white turnout in the polls. But Greene says "he's never heard of such a thing."

4. He's a political mastermind
One "intriguing" possibility is that Greene is "some kind of political genius," says Terence Samuel at The Root. Could he be a "stealth savant" so accomplished in the "art of grassroots campaigning" that he could attract 59 percent of the vote "while escaping the notice of his opponent, his party and the media"? 

5. South Carolina just doesn't like Vic Rawl
Rawl, the Democrat "judge and former state legislator" who lost to Greene, is far from popular among South Carolina Democrats, notes Ryan Tracy at Newsweek. A survey conducted in May found that only 4 percent had a favorable opinion of him. But, "that's a strong indication that many S.C. Democrats simply didn't know who Rawl was either."

6. He's black
Race can sometimes "tip the balance" in elections where both candidates are virtually unknown, says Alan Abramowitz, a political science academic quoted in Newsweek. But even though "there are many African-American voters among South Carolina Democrats," Greene's photo was not on the ballot paper and — given his spectacularly low-key campaign approach — it's unlikely any would have known who he is.