Final answer:
The power of Mexico's ruling party, the PRI, was maintained through its control over the government and legislature, as well as its ability to enact policies that supported its agenda.
Step-by-step explanation:
The power of Mexico's ruling party, the PRI (Institutional Revolutionary Party), rested on its ability to effectively run a one-party state and maintain control over the government and legislature. The PRI dominated Mexican politics from the 1920s until the twenty-first century. Although there were regular elections and an expansion of voting, the majority of presidents and legislators were members of the PRI. This allowed the party to consolidate power and enact policies that supported its agenda. One example of this was the presidency of Lázaro Cárdenas, who focused on social reforms and implemented socialist policies to support workers in Mexico.