 He was assigned to the standing committee on lumber and manufactures.He was elected to the 21st Senate District (Marathon, Portage and Waupaca counties) as a "Liberal Republican" in 1876, succeeding Liberal Democrat Willis Silverthorn (also part of the Reform movement) who was not a candidate for re-election.Mumbrue polled 5,362 votes against 4,990 for Thomas McDill (Rep.).