Updated

A South Carolina lawmaker on Sunday suggested that new Democratic Senate nominee Alvin Greene may be intellectually incapable of participating in the general election race.

State Rep. Todd Rutherford told Fox News that he went to Greene's house to discuss with him how Greene succeeded last week in becoming the candidate to challenge Republican Sen. Jim DeMint in the November election, but he found it difficult to decipher an answer.

"About two questions into a conversation with him, it would become apparent that he is not probably fit to answer the questions befitting a Senate candidate," said Rutherford, a Democrat. "If he was put into this, then it is a joke that is funny to all the rest of us, but he doesn't get it -- because I don't know that his mental status is such that he can get it."

On Friday South Carolina authorities launched a formal investigation into Greene's unlikely win. The campaign of his vanquished opponent, Vic Rawl, said it too is looking into reports across the state from voters and poll workers who "experienced problems with voting for whom they intended."

A Rawl campaign spokesman said he believes that the outcome of Tuesday's election is "statistically impossible" and "South Carolinians would rather be 100 percent right than 90 percent uncertain." Greene won with about 60 percent of the vote.

Rutherford said he asked Greene whether his honorable but involuntary discharge from the U.S. Army last August was related to his mental state.

"When I asked him whether they had checked his mental health status, he seemed to suggest that doing so brought about racist implications and other things. He kind of ducked the issue," said Rutherford.

Rutherford added that based on his conversation with Greene about his military service he got the impression that Greene could have decided to spend the $10,400 needed to enter the South Carolina race, but "I doubt it very seriously."

As the questions mount over the selection of Greene, some have attributed it to the arbitrary alphabet since Greene's name appeared above Rawl's on the ballot. Rutherford said the Senate Democratic primary in South Carolina was low profile to begin with and probably "people just hit a button and had no idea who they were voting for."

But South Carolina Rep. Jim Clyburn, the House majority whip, said he could reach no conclusion except that Greene is a plant.

"I never said he was a Republican plant. I said he was someone's plant. ... I saw the patterns in this. I know a Democratic pattern, I know a Republican pattern and I saw in the Democratic primary elephant dung all over the place," he told CNN.

Senior White House Adviser David Axelrod said he also is trying to find an explanation for the improbable victory.

"The whole thing is odd. I don't really know how to explain it and I don't think anybody else does either," Axelrod said on NBC's "Meet the Press."

Axelrod said he thinks the people of South Carolina deserve the best nominee on the ballot, although he supposes Greene would argue that since he won the election, he is the best candidate.

"How he won the primary is a big mystery though, and until you resolve that I don't think he can claim to be a strong, credible candidate," he said.

Rutherford said Greene certainly is not like other politicians.

"My conversation with him was not with someone who is all about politics, has an agenda, and wants his 15 minutes of fame. He would've been just fine sitting in his house, which he apparently did the entire campaign. I don't think he ever left his house," he said.

"It's scary because you don't want to suggest that somebody who does not have what everybody else has can't run for office, but it's also the fact that he won, so what do you do?” Rutherford asked.