...Jessica Mendoza, a 27-year-old outfielder on the United States Olympic softball team, does not hesitate to speak her mind about the killings in Darfur. But Ms. Mendoza stops short of publicly condemning China, which has close ties to the government of Sudan, because she says it is impolite to criticize her Olympic hosts and because one of her sponsors, Nike, has a major marketing presence in China... Although it is uncommon for sponsors to bar athletes from expressing political views, that could change if the situation worsens in Tibet and more athletes begin to speak out, said Alison Barnwell, a former athlete marketing coordinator for the U.S.O.C. [US Olympic Committee]... Anne Putz, Reebok’s [part of Adidas] head of corporate public relations, said in a statement that the company does not prohibit its athletes from expressing personal opinions... A Nike spokesman said that the company does not limit or censor athletes’ comments. “Over the years, Nike athletes have spoken their mind on issues, and we support our athletes’ right to do so,” KeJuan Wilkins, a Nike spokesman, said in a statement.