Hillary Clintons healthcare plan of 1993. In a letter to Mrs. Clinton, then Agriculture Commissioner expressed support for the ill-fated overhaul plan. Many are inclined to ignore this because in addition to being an eighteen year old letter, everybody knows Rick Perry had been a Democrat before becoming a Republican, so the thinking is that this should present no problem. Unfortunately, Rick Perry had already changed parties in order to run for the post as Agriculture Commissioner, the post in which he served at the time of the letter.
Please read the alleged "smoking gun" letter if you haven't.
He is not "in favor of HillaryCare," he's writing as Ag Comm to Hillary at the start of her healthcare task force telling her to consider the needs and problems of farmers, rangers and rural communities as she proceeds.