Klein was born in the Austro-Hungarian Empire in 1886, and received his education in the
common schools of that country. In 1903 he moved to the United States, coming directly to Milwaukee. He became a machinist and eventually found a long-term job with the Chicago & Milwaukee Railway. He became active in the trade union movement and the Milwaukee Socialist party.
He ran for re-election in 1920, but was defeated by Republican Martin M. Higgins, with 1,206 to 2,185 for Higgins (there was no Democrat in the race).[3]
