He served in the Legislative Assembly of Alberta from 1945 to 1967 as a member of the Social Credit caucus in government.

Halmrast first ran for a seat to the Alberta Legislature as a Social Credit candidate in a by-election held in the electoral district of Warner on August 6, 1945.

[1] In the 1948 general election Halmrast defeated Liberal candidate William Colliton in a two-way race.

[2] In the 1952 general election Halmrast defeated Liberal candidate George Snow by a landslide in his third two-way race in a row.

[4] In the 1959 general election Halmrast defeated Liberal candidate Mark Stringam in his fifth consecutive straight fight.