Career
Born in Kristiania, he took an education as a book printer. Having founded his own printing press in 1897, he moved it from Kristiania to rural Jessheim in 1902. Here, he founded the newspaper Akershusingen, renamed to Romerikes Blad in 1904.
He was the editor-in-chief of this newspaper for some time.
The newspaper still exists, and has a circulation of about 38,000. Halvorsen also edited Akershus Social-Demokrat from 1916 to 1917.
He also served one term, from 1913 to 1915, in the Parliament of Norway, representing the rural constituency of Mellem Romerike. He was later a deputy for Harald Halvorsen.
From 1908 to 1912 he was chairman of the county chapter.
However, as the Labour Party and the Social Democratic Labour Party reconciled in 1927, he rejoined Labour and sat on the county board for a second period, from 1927 to 1937.