|President Calderon's ruling National Action Party was roundly beaten in the elections, exit polls suggest [GALLO/GETTY]
Mexico's main opposition party is set for a decisive election victory in the country's most populous state, exit polls show.
Eruviel Avila, the candidate for the Institutional Revolutionary Party (PRI), had a "clear" lead over his rivals to be the next governor for the state of Mexico, which rings the capital, Mexico City, the Milenio Television reported on Sunday, citing exit polls.
The early figures suggested that President Felipe Calderon's conservative National Action Party (PAN) was on track for its worst electoral outing in the state for almost a generation, dealing a blow to his government.
Avila, the former mayor of Mexico state's largest municipality of Ecatepec, was backed by Enrique Pena Nieto, the outgoing governor who had been an early favourite to win back the presidency for the PRI in the presidential polls due in July 2012.
Another television exit poll showed the PRI leading with 64 per cent of the vote, which, if confirmed, would be the best result for the party in the state since 1987.
The TV Azteca poll showed the PAN slip into third place with just 13 per cent of the vote, and that the Demoratic Revolution Party (PRD) candidate had come in second.
The PRI is hoping that Pena Nieto's bid for the presidency will be boosted by the results in this election.
TV Azteca exit polls also gave the governorships in Coahuila and Nayarit, where polls were also held on Sunday, to the PRI.
Analysts say that while a clean sweep of the state elections on Sunday would be significant, a victory in 2012 was far from certain.
"Even though these state elections are important and they put the PRI in a clear lead for next year's presidential election, we still think (2012) is going to be a lot closer than polls are showing," Carlos Ramirez, an analyst with the Eurasia Group, said.
Laura Carlsen, the director of the Americas programme at the Centre for International Policy, told Al Jazeera that the state elections were "critical" when viewed in relation to the 2012 presidential polls.
"[The PRI] appears to have won by a landslide, and this means that they're very well positioned to go into these elections. It was critical because Mexico state is a very powerful state and it is a power centre for the PRI," she said.
"When the PAN [...] came into power [...] people expected changes and they didn't see it. And then that party has also brought the country to a critical state because of the drug war that was launched. That has led to 40,000 people dead in the country and a general situation of chaos, not only because of the violence but because of the erosion of political institutions."
Some voters remain wary of the PRI's autocratic past, as its 70-year rule was often dogged by accusations of vote-rigging and corruption.
Carlsen said that there was "mounting evidence of the scandalous use of public funds in this Mexico state election, as well as vote buying", pointing the finger at the PRI.
"One of the other critical things is that the Mexican people and the Mexican electoral institutions will have to be repaired ... for the next elections, because another thing that we saw clearly [in these elections] was that the electoral institutions ... were unable to stop some of the electoral law violations that the PRI put into place: by using excessive propaganda, by going over the spending limits," she said.
The states of Coahuila and Nayarit have seen a dramatic rise in drug-related murders and violence in the past year, and Calderon's party has taken a hit in public opinion for it.
More than 40,000 people have been killed in drug-related violence since 2007.
"The violence is always getting closer, you see it touching your family, your neighbors," said Israel Segura, 33, a vendor casting his vote in Ecatepec.
On the eve of the election, five dismembered bodies were found and two people died in a violent shootout in the state of Mexico, local media reported.
Flooding caused by heavy rains had also caused the emergency relocation of more than 170 voting booths in two of the state's largest cities.