The issue exploded Monday night when Representative Michele Bachmann and former Senator Rick Santorum attacked Gov. Rick Perry of Texas during a debate for issuing an executive order requiring sixth-grade girls to be vaccinated against the human papillomavirus, criticizing the order as an overreach of state power in a decision properly left to parents. Later, Sarah Palin, who has yet to announce her 2012 intentions, also found fault with Mr. Perry.  The issue pushes many buttons with conservatives: overreach of government in health care decisions, suspicion that sex education leads to promiscuity and even the belief — debunked by science — that childhood vaccinations may be linked to mental disorders.  On Tuesday, Mrs. Bachmann, of Minnesota, raised that concern by suggesting that Mr. Perry had put young girls at risk by forcing “an injection of what could potentially be a very dangerous drug.” Appearing on NBC’s “Today” show, she recounted that after the debate in Tampa, Fla., a tearful mother approached and said her daughter had suffered “mental retardation” after being vaccinated against HPV. “It can have very dangerous side effects,” Mrs. Bachmann said.  The focus on Mr. Perry’s record on the issue put him on the defensive during a debate for the second week in a row, this time among his core constituency of Tea Party voters.  “It’s the perfect storm of an issue,” said Craig Robinson, a former political director of the Republican Party of Iowa, noting that Mr. Perry, the front-runner in recent polls, was being attacked from his right flank. “You could tell these blows landed and affected him.”  Although Mrs. Bachmann called the HPV vaccine dangerous, a report last month from the Institute of Medicine, which advises the government, found that it was generally safe. There is no evidence linking it to mental retardation.  The vaccine is strongly recommended by medical groups, including the American Academy of Pediatrics and the American Cancer Society, to prevent cervical cancer, which kills about 4,000 women in the United States annually.  The recommended age of vaccination for girls is 11 or 12, before they become sexually active. But only Virginia and the District of Columbia require vaccination for middle school entry, according to the cancer society.  Dr. Deborah Saslow, the cancer society’s director of breast and gynecological cancer, said it did not advocate requiring HPV vaccinations before entering middle school, since parents and even doctors need more time to get used to the idea of the vaccine and to accept that it is safe.  When Mr. Perry issued his executive order in 2007, he made Texas the first state to require vaccinations, although parents could opt out. The order was instantly controversial — the State Legislature overturned it by bipartisan majorities before it could be carried out — and criticisms were raised at the time that Mr. Perry was doing a favor for a former chief of staff, Mike Toomey, who was then a lobbyist for Merck, the maker of the first HPV vaccine on the market, Gardasil.  Merck was lobbying legislatures around the country at the time to require Gardasil for middle school girls, but amid criticism — led by conservative groups worried that it would promote early sex — the company withdrew the campaign.  Mrs. Bachmann, whose campaign had lost the wind in its sails ever since Mr. Perry entered the nomination race last month, used Monday night’s debate to accuse the governor of what she later called “crony capitalism” because of his ties to Mr. Toomey and Merck, which donated to his campaign. Ms. Palin echoed those charges on Fox News.  Mr. Perry, who said during the debate that he should have worked with the Texas Legislature, not issued an executive fiat, dismissed any suggestion that he could be bought for a mere $5,000 contribution (records show he actually received $30,000 from Merck).  A spokesman for Mr. Perry, Mark Miner, called Mrs. Bachmann’s and others’ comments “ridiculous.”  “You’re going to have candidates grasping for straws and grasping to get attention,” Mr. Miner said. “However, Governor Perry will continue focusing on issues that matter to people such as creating jobs and improving the economy.”  Mrs. Bachmann said she would continue to raise the vaccine issue because it shows “very real distinctions” between herself and Mr. Perry.  Republican strategists also said that the issue was unlikely to go away, and that Mr. Perry’s actions in 2007 raised questions not only among social conservatives, but also with party members and independents who would find it an overreach of executive authority.  “I think it undercuts Governor Perry’s ability to criticize Governor Romney on health care,” said Steve Duprey, the Republican national committeeman for New Hampshire, referring to Mr. Romney’s support of an individual mandate in Massachusetts. “We’re a state that takes a dim view on the government compelling us to do anything.”  Mrs. Bachmann’s suggestion that HPV vaccines could be dangerous caused some influential conservative bloggers and broadcasters to suggest that she had carried the attack too far, raising questions about her judgment in echoing the thoroughly debunked views that vaccines are linked to autism or other mental illness.  Rush Limbaugh on Tuesday said she “may have jumped the shark” with her linking of HPV vaccines to mental retardation.  Appearing on the talk show of another conservative host, Sean Hannity, Mrs. Bachmann backpedaled a bit. “I am not a doctor, I am not a scientist, I’m not a physician,” she said.
The unlikely issue has become the latest flashpoint among G.O.P. presidential candidates as they vie for the support of social conservatives.