Why did theodore roosevelt decide to run against taft in the 1912 election?

Theodore Roosevelt and some Republican Party members did not want William Taft to be the party's nominee for president. So, they formed the Progressive Party, nicknamed the Bull Moose, to nominate Roosevelt and defeat Taft. In an interview with the Saturday Evening Post on May 4, 1912, Roosevelt stated that Taft had betrayed the people and the party ideals by not doing what he had promised before being elected.