He also ran for Governor and Lieutenant Governor of Wisconsin and later served as a political appointee under presidents Franklin Roosevelt and Harry Truman, serving in roles at the War Production Board, the United States Department of Commerce, and the United States Department of Agriculture.

[1] In 1930, rather than running for another term in the Assembly, Nelson ran for Wisconsin Senate, launching a primary challenge against incumbent R. Bruce Johnson.

[3] There was no Democratic nominee in the district, but Charles Peacock entered the general election race as an independent progressive candidate.

[6] In 1942, rather than running for re-election in the Senate, Nelson entered the Progressive Party primary race for Lieutenant Governor of Wisconsin.

[7] He defeated Henry J. Berquist in the primary,[8] but ultimately decided to withdraw from the race a month before the election to accept a federal appointment as deputy chief of the municipal government section of the War Production Board in Washington, D.C.[9] The Progressives replaced him with Berquist as their nominee for Lieutenant Governor, who went on to lose the general election to incumbent Republican Lieutenant Governor Walter Samuel Goodland.

Like many former Progressives, Nelson became aligned with the Democratic Party of Wisconsin and considered a return to elected office, but ultimately did not run again.