While the consequences of the Smoot-Hawley Tariff have been a subject of dispute, few would deny that it stimulated a cascade of retaliatory tariffs by foreign governments which made it very hard for American businessmen and farmers to sell goods overseas. This took the American economy, already staggering after the Stock Market Crash of 1929, and shot it in the knee. The Smoot-Hawley Tariff may not have caused the Great Depression but it made it matters much worse.
When the Democrats returned to power they slowly began to reduce tariff rates and the Republicans with few exceptions have abandoned protectionism. Today, for the most part both political parties assert that government tariffs that either fatten the profits of poorly run businesses or keep alive jobs that do not make economic sense anymore, cheat the vast majority of Americans of the benefits of affordable goods and make it harder for us to sell our products overseas.
So it looks like it was your precious Roosevelt, Mr. New Dealer, who helped roll back tariffs.