In the 1888 presidential election, Roosevelt campaigned in the Midwest for Benjamin Harrison. President Harrison appointed Roosevelt to the United States Civil Service Commission, where he served until 1895. In his term, Roosevelt vigorously fought the spoilsmen and demanded enforcement of civil service laws. Close associate, friend and biographer, James Bucklin Bishop, described Roosevelt's assault on the spoils system indicating that,
The very citadel of spoils politics, the hitherto impregnable fortress that had existed unshaken since it was erected on the foundation laid by Andrew Jackson, was tottering to its fall under the assaults of this audacious and irrepressible young man...Whatever may have been the feelings of the (fellow Republican party) President (Harrison) — and there is little doubt that he had no idea when he appointed Roosevelt that he would prove to be so veritable a bull in a china shop—he refused to remove him and stood by him firmly till the end of his term.
During this same time, the New York Sun described Roosevelt as "irrepressible, belligerent, and enthusiastic"
In spite of Roosevelt's support for Harrison's reelection bid in the presidential election of 1892, the eventual winner, Grover Cleveland (a Bourbon Democrat), reappointed him to the same post.