WASHINGTON (AP) — The U.S. immunologist who says he lost his government job because he warned the Trump administration to prepare for the coronavirus pandemic isn't backing off his bleak forecast.

Dr. Rick Bright is telling Congress that America faces the "darkest winter in modern history" unless its leaders act decisively to prevent a rebound of the coronavirus.

Bright appeared Thursday before the House Energy and Commerce Committee.

In prepared testimony, Bright says failing to develop a national coordinated response, based in science, could mean the pandemic will get far worse and cause unprecedented illness and fatalities.

President Donald Trump has called Bright "a disgruntled employee."