I'm curious because back in October 2003 I did a cartoon called Multiple Choice Mitt, the original of which was purchased by the ACLU of Massachusetts and given as a gift to Massachusetts Speaker of the House Salvatore F. DiMasi. The cartoon was actually about the death penalty and not other issues, but it's just a weird coincidence, so I'm wondering where I got the term. Is it just the fun alliteration? I tried googling it and I couldn't find any pre-2007 examples, but there have to be some out there as I believe I was referring to something in particular (yes, I'm losing my memory at the age of 26).
Update: I looked back at my notes from 2003 and discovered that I was referencing the same thing the lefty bloggers are--a famous debate between Ted Kennedy and Mitt Romney in 1994, when Romney claimed that he was strongly pro-choice and Kennedy countered that he was really "multiple choice". Mystery solved!