Exit polls from three governor's races in Mexico show candidates from the main opposition Institutional Revolutionary Party are winning in the country's most populous state.

Television polls show Eruviel Avila, PRI's candidate in the state of Mexico, won an estimated 64 percent of the vote, while Alejandro Encinas, a member of the Democratic Revolution Party was in second place with 23 percent.

Exit polls also show the PRI leading in elections in Coahuila and Nayarit states.

The PRI faced challengers from President Felipe Calderon's conservative National Action Party, which attempted to partner with the leftist Democratic Revolution Party to defeat the PRI in Coahuila and Nayarit.

Analysts see Sunday's vote as a possible indicator of what to expect in next year's presidential election.

The PRI's current governor in Mexico state, Enrique Pena Nieto, is considered a front-runner in the 2012 presidential race. Pena Nieto could face President Calderon, who analysts suggest may be vulnerable because his country's escalating drug violence has diminished his popularity and the influence of his party.

Tens of thousand of people have died in drug violence since Mr. Calderon took office in 2006 and began a campaign against the drug cartels.