In the next years, Newcomb continued to work in Hollywood, representing Barbra Streisand and Natalie Wood, among other celebrities, and working for film productions, such as "Hello, Dolly!" (starring Streisand) and "Ordinary People". She was an information specialist in the United States Information Agency and a consultant to the Justice Department, after helping in the senatorial campaign of Robert Kennedy in 1964. Newcomb was also Kennedy's campaign manager in the 1968 presidential election, working for him until his assassination. In 1970, Newcomb campaigned for democrat Eunice Kennedy. A year prior, she founded the Pickwick Public Relations agency with Pat Kingsley and Lois Weber Smith. In 1985, Newcomb was named vice-president of the motion picture production at MGM.