(WASHINGTON) — Robert F. Kennedy Jr.’s personal attorney previously lobbied the Food and Drug Administration to revoke the approval of the polio vaccine, highlighting an influential Kennedy ally who, sources tell ABC News, has been helping interview candidates for top health jobs in the incoming Trump administration.

Aaron Siri, a partner at the law firm Siri & Glimstad, has long fought against the widespread prevalence of vaccines. He has also filed petitions seeking to pause the distribution of other vaccines, including Hepatitis B, and to revoke the emergency use authorization of COVID-19 vaccines.

The polio petition was made on behalf of one of Siri’s clients, the Informed Consent Action Network (ICAN), a group founded by Del Bigtree, another close Kennedy ally who also has been involved in health-related transition matters, according to sources.

“Petitioner requests that the FDA withdraw or suspend the approval for [the polio vaccine] for infants, toddlers, and children until a properly controlled and properly powered double-blind trial of sufficient duration is conducted to assess the safety of this product,” Siri wrote.

The New York Times reported on the petition earlier Friday.

Siri did not respond to ABC News’ request for comment.

Kennedy, meanwhile, did not respond to written questions about whether he agrees with revoking the approval of the polio vaccine or if, as Health and Human Services secretary, he would intervene in the FDA’s review of Siri’s petitions.

The polio vaccine available in the United States is recommended for children and three doses offer at least 99% protection against severe disease, including paralysis, according to the CDC. Side effects are usually mild and go away on their own, the agency notes, and the vaccine has not been known to cause serious problems.

ABC News’ Youri Benadjaoud contributed to this report.

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