Robert F. Kennedy Jr.’s personal lawyer has previously lobbied the Food and Drug Administration to revoke approval of the polio vaccine, pointing to an influential Kennedy ally who, according to ABC News sources, helped Interviewing candidates for top health care positions Trump administration.

Aaron Siri, partner at Siri Law Firm & Glimstad has long been fighting against the widespread distribution of vaccines. He has also filed petitions to suspend distribution of other vaccines, including hepatitis B, and to revoke the emergency use authorization of COVID-19 vaccines.

The polio petition was filed 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 has also been involved in health-related transition issues, according to sources.

“The petitioner requests that the FDA withdraw or suspend approval (of the polio vaccine) for infants, young children and children until a properly controlled and properly conducted double-blind trial of sufficient duration is conducted to evaluate the safety of this product,” said 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 agreed with the revocation of the polio vaccine’s approval or whether, as Health and Human Services secretary, he would intervene in the FDA’s review of Siri’s petitions.

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

ABC News’ Youri Benadjaoud contributed to this report.