Chinese journalists, backed by 500 college students shouting slogans of support, delivered a petition Tuesday calling for press freedom and signed by more than 1,000 journalists in the first formal challenge to Communist Party censorship. "The time has come for an open press," said Li Datong, a journalist for the China Youth News and spokesman for the petition drive, which was sparked by the largest pro-democracy student protests since the founding of communist China in 1949. Li delivered petitions signed by 1,013 journalists from more than 30 newspapers and broadcast outlets to the All-China Journalists' Association, a government-sponsored umbrella organization for China's media. About 500 students from at least six Beijing campuses marched to support the journalists, chanting for press freedom outside the Communist Party organ People's Daily and watched by about 30 armed police inside the compound. The march marked the first off-campus activity in five days by students, who have been electing leaders to represent them in talks with officials.