It is common for parties forced into opposition to accuse any party that wins an election of electoral fraud of some form. Kenya's first multi-party election in 26 years was impaired by the cancellation of polls in several constituencies as a result of suspected ballot rigging in 1992. In some instances, parliamentary and presidential ballot boxes were mixed up and polling stations were opened past scheduled hours. Some Kenyan officials were accused of advantageously filling in ballots for citizens unable to complete them themselves. Benazir Bhutto, former prime minister of Pakistan, accused her rival of buying votes in order to displace her in 1990. Mexico's 1991 victory of the ruling Institutional Revolutionary Party resulted in charges of ballot rigging raised by the opposition, despite government assurances of new electoral machinery designed to eliminate fraud that had long plagued Mexico's political system. President Yeltsin of Russia was accused of rigging the national elections in 1993, partly by banning parties because they had not met registration requirements. In 1993 the Republican Party in New Jersey (USA) was accused of paying church ministers to discourage black, pro-Democrat participation in the state elections. In 1994 international observers reported irregularities in the presidential election in Serbia.