Landis built a corporate law practice in Chicago; with the practice doing well, he deeply involved himself in Republican Party politics. He built a close association with his friend Lowden and served as his campaign manager for governor of Illinois in 1904. Lowden was defeated, but would later serve two terms in the office and be a major contender for the 1920 Republican presidential nomination. A seat on the United States District Court for the Northern District of Illinois was vacant; President Theodore Roosevelt offered it to Lowden, who declined it and recommended Landis. Other recommendations from Illinois politicians followed, and Roosevelt nominated Landis for the seat. According to Spink, President Roosevelt wanted "a tough judge and a man sympathetic with his viewpoint in that important court"; Lowden and Landis were, like Roosevelt, on the progressive left of the Republican Party. On March 18, 1905, Roosevelt transmitted the nomination to the Senate, which confirmed Landis the same afternoon, without any committee hearing; he received his commission the same day.