What is PRI?What was its role …

The Institutional Revolutionary Party (PRI) was very strong in Mexico till 2000. Several oppositional parties contested elections but never managed to win because of the PRI. There were many reasons behind it:
(i) The PRI used many dirty tricks to win the elections.
(ii) All those who were employed in government offices had to attend all the meetings held by the PRI.
(iii) Teachers of government schools used to force parents to vote for the PRI.
(iv) Media largely ignored the activities of opposition political parties except to criticize them.
(v) Sometimes the polling booths were shifted from one place to another in the last minute, which made it difficult for people to cast their votes.
(vi) The PRI spent a large sum of money in the election campaign for its candidates. Mexico did not conduct fair elections as every election was won by PRI.