Klain is one of Biden's closest confidants and first worked for the Democrat in 1989 when he was a U.S. senator. A fierce critic of Republican President Donald Trump's handling of the novel coronavirus pandemic, Klain was expected to be a key figure in Biden's response to the health crisis. “Ron has been invaluable to me over the many years that we have worked together, including as we rescued the American economy from one of the worst downturns in our history in 2009 and later overcame a daunting public health emergency in 2014,” Biden said in a statement.