A whistleblower who says he was removed from his government post for raising concerns about coronavirus preparedness told a congressional hearing on Thursday that the United States could face “the darkest winter” of recent times if it does not improve its response to the pandemic. Hours after President Donald Trump railed against him on Twitter, whistleblower Rick Bright testified to a U.S. House of Representatives panel about readiness for the outbreak. Bright was removed last month as director of the Biomedical Advanced Research and Development Authority, or BARDA, a part of the U.S. Department of Health and Human Services responsible for developing drugs to fight the coronavirus. “What we do must be done carefully with guidance from the best scientific minds. Our window of opportunity is closing. If we fail to improve our response now, based on science, I fear the pandemic will get worse and be prolonged,” Bright said during his testimony.