White House Budget Director Mick Mulvaney praised outgoing Economics Adviser Gary Cohn as a "one of the smartest people I've ever worked with."
Mulvaney, who was a South Carolina Republican congressman and founder of the conservative House Freedom Caucus before joining the White House, took to Twitter:
Cohn, 57, a registered Democrat who joined the White House to advocate for business-friendly economic principles, said Tuesday he was resigning, in an apparent rift over President Donald Trump's plan to impose tariffs on steel and aluminum exports.
"It has been an honor to serve my country and enact pro-growth economic policies to benefit the American people, in particular the passage of historic tax reform," Cohn said in a statement.
"I am grateful to the president for giving me this opportunity and wish him and the administration great success in the future."
President Trump praised Cohn for doing "a superb job in driving our agenda, helping to deliver historic tax cuts and reforms and unleashing the American economy once again.
"He is a rare talent, and I thank him for his dedicated service to the American people."