In 1888, he served as a delegate to the Republican National Convention, where he was the first to cast a vote for William McKinley, who was running for the party's presidential nomination.

[1] When the Cherokee Outlet was opened to settlement on September 16, 1893, causing a land-rush, Jenkins succeeded in securing a homestead in Kay County, where he practiced law until he entered government service.

Jenkins assumed that position in June 1897, and would serve for four years until President McKinley elevated him as Territorial Governor, effective May 13, 1901.

[1] Questions of Governor Jenkins's fidelity arose following the renewal of contracts with the Oklahoma Sanitarium Company for the care of the insane in the Territory.

Newly elevated President Theodore Roosevelt immediately received demands to remove Governor Jenkins from office.

Territorial Secretary William C. Grimes became acting Governor until President Roosevelt appointed Thompson Benton Ferguson to the Governorship on December 9, 1901.