Theodore Roosevelt founded a party that called for wide-ranging progressive reforms.
Theodore Roosevelt Jr. ( [ ˈroʊzəvɛlt ] ; October 27 , 1858 -- January 6 , 1919 ) was an American statesman , author , explorer , soldier , naturalist , and reformer who served as the 26th President of the United States from 1901 to 1909 . He failed , walked out , and founded a third party , the Progressive , so-called `` Bull Moose '' Party , which called for wide-ranging progressive reforms .