Uehara took a critical stance against the formation of the Taisei Yokusankai, and in 1941 formed an anti-Yokusankai group with Hatoyama and Yukio Ozaki; however, the group was defeated in the 1942 General Election.
Considered successful in his mission to establish a profitable for the Japanese Empire economy in Manchouria, he was recalled to Japan in 1940 where he was selected to serve as chief "Project Department" inside the Finance Ministry to implement the economic reorganization of Japan under the Taisei Yokusankai in the second Konoe Cabinet.