The election of South Carolina's Democratic Senate candidate should be questioned, according to Senior White House Advisor David Axelrod.

NBC's David Gregory asked David Axelrod Sunday if Alvin Green's election was legitimate.

"It doesn't appear so to me. It was a mysterious deal," Axelrod responded. "The whole thing is odd. I don't really know how to explain it and I don't think anybody else does either."

"I think the Democrats of South Carolina deserve a strong, credible candidate. He would argue I suppose that he won the primary so that would be him. How he won the primary is a big mystery, and until you resolve that I don't think he can claim to be a strong, credible candidate," said Axelrod.