A good article on The Hill describes the difficulty Perry will have in attacking Romney on health care.
#1) Perry leads a state that has the highest uninsured rate in the country. Contrast that with Romney who helped Massachusetts become the state with the lowest uninsured rate in the country.
#2) 10th Amendment - Perry has said that he strongly supports states rights in crafting their own solutions to their own problems. Perry has even stated that MA had every right to do what it did.
#3) A letter Perry wrote to Hillary Clinton is making headlines because in the letter Perry lauds the Ms. Clinton for her efforts to reform healthcare.