Entertainer Joan Rivers, director John Landis and writer/director Nora Ephron have endorsed a boycott of Colorado, at the request of the Gay and Lesbian Alliance Against Defamation/Los Angeles.And a number of organizations, individuals and municipalities are expected to weigh in on the issue in the next few weeks as the movement to boycott the state appears to be gathering steam. Yesterday, New York City Mayor David Dinkins issued a strongly worded statement in which he said he will not attend a mayors’ conference in the state. He also has forbade city employees from traveling to Colorado on city business. The actions follow Colorado’s recent passage of Amendment 2, which voids and prohibits legislation protecting gays and lesbians from discrimination, and prevents the state courts from hearing cases involving discrimination based on sexual orientation. GLAAD/LA and other groups have asked members of the entertainment industry to pledge not to work or vacation in Colorado in protest. Others who had already endorsed a boycott or canceled plans to travel to the state include Whoopi Goldberg, Jonathan Demme, Rick Rosenberg, Howard Rosenman, the American Foundation for AIDS Research, Laurel Entertainment, the city council of Atlanta, the National Organization for Women, the National Center for the Social Studies, Coalition of Labor Union Women, the American Assn. of Law Libraries and Boycott Colorado Inc., headquartered in the state. Barbra Streisand started the ball rolling, saying on Nov. 18 that people in the entertainment industry should boycott if asked to. However, on Nov. 24 at a press conference in Aspen, she said she had not called for a boycott. The boycott idea has been opposed by former 20th Century Fox owner Marvin Davis. Reportedly, Robert Wagner, Jill St. John and Reggie Jackson also are opposed to a boycott and rocker Don Henley and CAA chairman Michael Ovitz expressed displeasure with Streisand’s original remarks. Groups expected to address the issue in the days to come include the American Civil Liberties Union of Southern California, the National Gay & Lesbian Task Force, other city governments, and more entertainment industry figures. In his statement, Mayor Dinkins said yesterday he had sent a letter to the executive committee of the U.S. Conference of Mayors, advising them that he would not travel to the state for their annual meeting, and suggested the confab relocate.