From their base in the 1968 student movement, the PRT grew quickly, soon gaining bases of support among some telephone, electrical, nuclear, and hospital workers. By the 1980s, it was the largest far-left party to challenge the ruling Institutional Revolutionary Party (PRI). In 1981, the federal government recognized the PRT as an official nationwide party. In the 1982 general elections, it was also the first Mexican party to raise gay rights as a campaign issue; the party fielded several openly gay candidates for the Chamber of Deputies. It also entered informal alliances with the other main party on the far left, the United Socialist Party of Mexico (PSUM).