According to Wikipedia, he ran for Congress in 2010 on a promise to get rid of federal income taxes and had become involved with several Tea Party organizations.
So basically he went from being a corrupt, protectionist Democratic HP to being a regressive de facto Republican HP.
He supported abolishing the IRS and getting rid of the income tax for years while he was still in Congress. As far as I see he hadn't really changed much on policy but he found comfort in the Tea Party once he was released from prison.
