President Trump attacked the former top vaccine official who filed a whistleblower complaint against the administration hours before the official’s scheduled testimony before a House subcommittee.

Rick Bright, the former director of the Biomedical Advanced Research and Development Authority, has alleged that he was demoted for pushing for more evidence regarding hydroxychloroquine, the drug touted by Trump as a possible treatment for the coronavirus. He is expected to testify that the United States could face “unprecedented illness and fatalities” from COVID-19 without additional preparation when he appears before the House Energy and Commerce Subcommittee on Health later Thursday.