NICHOLAS KAMM/AFP via Getty Images House Speaker Nancy Pelosi called President Donald Trump a "psychopathic nut" on Thursday evening.
Trump has resisted acknowledging President-elect Joe Biden's win and continues to challenge the election results.
His campaign has not won any of the almost two dozen lawsuits filed across several states based on unsubstantiated claims of voter fraud.
Biden has called on Congress to act swiftly and approve a new stimulus package to combat the coronavirus pandemic and help millions of financially-struggling Americans before the year ends.