[8][9] In addition, Belknap was an active member of the Masons and the local Odd Fellows lodge.

Shortly after arriving in Prineville, he ran for the county superintendent of schools position, but lost the election.

[12] Over the next decade, he continued to support the Republican Party and its candidates, attending both county and state conventions.

[15] In the Republican primary, Belknap and George H. Merryman (another physician) were nominated for the two District 21 seats.

[16][18] Belknap took his seat in the Oregon Legislative Assembly when the 24th regular session was called to order on January 14, 1907.

[21] Belknap and Hazen A. Brattain won the Republican primary and then went on to win the two District 21 seats in the general election.

During the 1909 session, which began on January 11, Belknap served on the elections, medicine and pharmacy, and public lands committees.

[23][24][25] A month later, Belknap and his fellow legislators were called back for a two-day special session before adjourning for the remainder of the biennium.

[26] Following the close of the special session, Governor Frank W. Benson appointed Belknap as a delegate to Oregon's Good Roads Convention which meet during the summer of 1909.

The state Republican convention endorsed Belknap and W. Lair Thompson for the two District 21 representative seats.

[28][29] In the general election, Belknap and Thompson won the district's two seats, easily defeating the only Democrat in the race.