Dr. Fauci repeatedly lashed out at Republican senators during a bad-tempered Senate hearing Tuesday, accusing Sen. Rand Paul of Kentucky of fueling threats against the White House chief medical adviser and his family before referring to Sen. Roger Marshall of Kansas as a “moron” on a hot mic.

Fauci and Paul have repeatedly clashed during Senate hearings in recent months and engaged in yet another verbal throwdown before the Senate Health, Education, Labor and Pensions Committee.

At one point, Fauci accused Paul of claiming he was “responsible for the death of 4 to 5 million people, which is really irresponsible.”