Pazdur privately mused last month about retiring from the Food and Drug Administration or returning to his old job at the agency as he raised concerns about the legality and pace of agency plans to expedite drug decisions, The Washington Post previously reported.

Pazdur’s retirement follows tensions with FDA Commissioner Marty Makary, who has touted multiple initiatives to boost the agency’s efficiency. Pazdur had questioned plans by Makary aimed at significantly shortening review times for drugs that are aligned with the country’s priorities. Pazdur had initially turned down the job as the top drug regulator.