In 1867, Sanderson advanced to the Senate to represent the 25th Senate District (Columbia County) (he succeeded Jonathan Bowman in the Senate, and was succeeded in the Assembly by Ira Ford, both of the same party with himself); and was assigned to the committees on roads, bridges and ferries; and on engrossed bills. He was also a member of the Board of Regents for the University of Wisconsin.The Legislative Manual, of the State of Wisconsin; Comprising Jefferson's Manual, Rules, Forms and Laws, for the Regulation of Business; also, lists and tables for reference Sixth Annual Edition. Madison: Atwood and Rublee, State Printers, 1867; pp. 155, 168, 169, 204 He returned in 1868, although by that time the Union Party label had been abandoned; he was assigned to the committees on privileges and elections; on agriculture; and on railroads (chairing the latter). He was re-appointed to a new term as a regent, and served in that capacity through 1873, including serving on the executive committee of the Board of Regents.The Legislative Manual, of the State of Wisconsin; Comprising Jefferson's Manual, Rules, Forms and Laws, for the Regulation of Business; also, lists and tables for reference Seventh Annual Edition. Madison: Atwood and Rublee, State Printers, 1868; pp. 167, 169–170, 198 He was succeeded in 1869 by fellow Republican William M. Griswold.
