Upon leaving school, he moved to Milwaukee, where he learned carpentry and practiced that profession, later going into the teamster, trucking and garage business.
He had never held public office until his successful 1928 bid for the Assembly,[2] succeeding fellow Socialist Julius Kiesner.
Kehrein was elected to the Milwaukee County Board in the spring of 1932, serving in both capacities until his Assembly term expired in January 1933.
[3] He was succeeded by Democrat George Weissleder, who had served in the Wisconsin State Senate 20 years before.
[5] In 1940 he ran as a Republican for the 2nd Milwaukee County Assembly district held by Andrew Biemiller (himself a former Socialist, but by the with the Progressives).