Rep. Darrell Issa (R-Calif.) isn't satisfied with the White House's explanation of the Sestak-Clinton imbroglio and is now charging the White House with possible "witness tampering."

The ranking member of the House Government Reform and Oversight Committee, Issa told Fox News on Friday afternoon that he didn't buy the argument made by White House Counsel Robert Bauer that Sestak was offered only a non-paid advisory position.

“I see a lot of inconsistencies. Casual conversation, non-paid position, that’s very inconsistent with what Congressman Sestak said before and it makes us question whether there’s been witness tampering in this case," Issa said.

He even compared the White House's actions to those of the Nixon administration.

“[A]t this point, 10 weeks later, lots of witness tampering or at least witness interrogation by people who are self-serving, we’re beginning to go down that same road" as Nixon, Issa said.

He also accused the White House of coordinating its response with Sestak to get the story straight.

"Absolutely" they coordinated, Issa said. "We learned that they had contacted Joe Sestak’s brother, his campaign manager and they obviously did coordinate the statement.”