Katherine Shaw has posted this draft on SSRN (forthcoming Election Law Journal).  Here is the abstract:

 This piece excavates the history of the Millionaire’s Amendment, a short-lived provision of campaign finance law that played a significant role in Barack Obama’s successful 2004 Senate campaign. It argues that beyond the Amendment’s role in that single, fateful race, it supplies a useful test case for examining competing paradigms for regulating money in politics.