Lyndon Baines Johnson, often referred to by the initials LBJ, was an American politician who served as the 36th president of the United States from 1963 to 1969. Formerly the 37th vice president from 1961 to 1963, he assumed the presidency following the assassination of President John F. Kennedy. A Democrat from Texas, Johnson also served as a United States Representative and as the Majority Leader in the United States Senate.