Sen. Bernie Sanders apologized on CBS News Monday evening for a Guardian op-ed written by a campaign surrogate that claims his Democratic presidential rival Joe Biden has a "big corruption problem."

Driving the news: In the op-ed, published earlier Monday, law professor Zephyr Teachout, claims Biden "has perfected the art of taking big contributions, then representing his corporate donors at the cost of middle- and working-class Americans." In his CBS interview, Sanders said it's "absolutely not my view that Joe is corrupt in any way" and he's "sorry that that op-ed appeared."

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Editor's note: This article has been updated with more details of the op-ed and comment from Sanders.