"All of his trade policies may not only cause the lowering of our imports but it could cause retaliation on the part of our exporters and so that could contract trade," Lee, head of North American economics at Citi, told CNBC's "Power Lunch."
"We think that would be the source of a recession sooner than later under Trump."
Clinton, on the other hand, will probably continue the current trade policies, he said.
Lee co-authored Citi's latest note on the economic impact of either a Clinton or Trump presidency. The firm said there is a 65 percent probability that Clinton will win.