Senators John F. Kennedy and Lyndon B. Johnson pledged yesterday that if elected they will "use the full power of the executive branch of the Government to assure the early enactment" of District home-rule legislation.
     The Democratic presidential nominee made the pledge in a letter to W. John Kenney, Chairman of the District Democratic Central Committee
     Kennedy said he and his running mate will continue to urge prompt ratification by the States of the constitutional amendment that would give District residents the vote for President and Vice President.
     But, Kennedy said, he and Johnson will not allow this "to deter us from the basic task of securing local self-government for the District."
     Kennedy said he is confident that his and Johnson's efforts for self-government will "have the full cooperation of the party's floor leadership in the Congress."