He once commented that Roosevelt "ought more often to have admitted the legal way of reaching the same ends."

Taft alienated many liberal Republicans who later formed the Progressive Party, by defending the Payne-Aldrich Act which unexpectedly continued high tariff rates. A trade agreement with Canada, which Taft pushed through Congress, would have pleased eastern advocates of a low tariff, but the Canadians rejected it. He further antagonized Progressives by upholding his Secretary of the Interior, accused of failing to carry out Roosevelt's conservation policies. In the angry Progressive onslaught against him, little attention was paid to the fact that his administration initiated 80 antitrust suits and that Congress submitted to the states amendments for a Federal income tax and the direct election of Senators. A postal savings system was established, and the Interstate Commerce Commission was directed to set railroad rates. In 1912, when the Republicans renominated Taft, Roosevelt bolted the party to lead the Progressives, thus guaranteeing the election of Woodrow Wilson. Taft, free of the Presidency, served as Professor of Law at Yale until President Harding made him Chief Justice of the United States, a position he held until just before his death in 1930. To Taft, the appointment was his greatest honor; he wrote: "I don't remember that I ever was President.".