Representative Michele Bachmann (R-MN) thinks she’s found an issue with which to drive a wedge between Governor Rick Perry (R-TX) and conservative voters, and she won’t let go of it. At Wednesday’s CNN/Tea Party Express debate, Bachmann railed against Perry’s decision to order the vaccinations of Texas schoolgirls (with a parental opt-out provision) for HPV, the virus that causes cervical cancer. On Thursday Bachmann went on Good Morning America to hammer home the point, claiming—against all known medical science—that the HPV vaccine can cause mental retardation in the 11- and 12-year-old girls who would have been vaccinated. (The Texas legislature overturned Perry’s executive order. Perry now apologizes for not promoting the initiative legislatively and for making vaccination opt-out instead of opt-in.)

Undeterred by the widespread derision of her ignorant fear-mongering, Bachmann hit Perry again on Friday with a web video titled “No to Obamacare and Perrycare.”

At first glance this might seem to be a strange, rather minor, issue for Bachmann to fixate on. No one is suggesting that as president Perry would require vaccination of every school girl in America. Even to the most right-wing Republican, there are more pressing issues that the president will face, such as the federal budget deficit.

The reason Bachmann is sticking with the attack is that she is using it as a synecdoche for Perry’s larger weakness: that he is a George W. Bush clone. To Tea Party conservatives, Bush betrayed them by being in the pocket of corporations and using the government to advance their interests. After all, the right-wing reaction that has shaken this country actually began before the 2008 election, when angry mobs bullied their Republican congressmen into voting against the TARP bailouts that saved the global economy from total catastrophe.

Perry holds Bush’s former office, he sounds a lot like him, and he is a loyal servant of Texas business interests. Hitting Perry for “crony capitalism” as Bachmann did on Good Morning America and again in her web ad, is a way of linking him to that legacy. Perry, of course, is aware of this risk, which is why he has criticized Bush, saying Bush was not a “real fiscal conservative.”

Like Bush, Perry is a former cheerleader who might seem a little too much of a Good Ol’ Boy to some folks. As the Washington Post reports, women are less likely to support Perry than men, which is surely also part of Bachmann’s calculation. That’s why she keeps invoking the specter of “innocent” girls being subjected to vaccination, as if preventing someone from getting cancer is a punishment. Bachmann’s ad is full of word choices carefully crafted to hit those notes. It reads, in part:

There are many important issues in this presidential campaign—including the role of government, abuse of executive power and crony capitalism. As a mother of three daughters, I believe that parents are the ones who should decide whether or not their young daughters should receive injections for sexually transmitted diseases. These are decisions that are best left to parents, the children and their doctors and should take into consideration the child’s health and the family’s values.

Whether its Obamacare or Perrycare I oppose any governor or president who mandates a family’s healthcare choices and violates the rights of parents on these issues—especially if the decision-making process occurs behind closed doors, bypassing legislative action, and favors campaign contributors over families.

Note how Bachmann discusses “injections for sexually transmitted diseases,” as if the vaccine gave you a STD rather than preventing it.

Bachmann’s focus on this marginal issue is basically an act of desperation. Perry has supplanted her as the leading contender of the right wing of the Republican Party since his August entry into the presidential race. Bachmann needs to win back supporters from Perry if she is to prevent it from becoming a two-person race between Perry and Mitt Romney. Since Bachmann has never governed, and has used her legislative perches mainly to burnish the purity of her conservative credentials rather than to pass legislation, she cannot present herself as, say, a more accomplished economic manager than Perry or Romney. That leaves her only with the option of attacking them as insufficiently conservative. Unfortunately for her, Perry’s record is so right-wing that she has few means by which to do it.