An election Sunday in Mexico's most populous state will determine its next state -- but could also position the candidates for the battle to become president in 2012.

Eruviel Avila headed into the closely watched vote with a 30-percentage-point lead for the Institutional Revolutionary Party, or PRI, which has never lost the governorship in more than 80 years. But the PRI needs a commanding victory to create momentum going into the July 2012 national election, where it wants to regain the presidency it lost in 2000 after 71 years of uninterrupted rule.

The front-runner in presidential polls, Enrique Pena Nieto, is the current PRI governor of Mexico state, home to 15 million people and the sprawling, impoverished suburbs that ring Mexico City.

The other two major parties, trailing in the polls and lacking the coalitions that have defeated the PRI in other states, are warning voters that backing the PRI is backing a return to the past, when the "dinosaurs" wielded power through coercion, corruption and intimidation.

"I'm confident that today will be a fiesta for democracy," said Avila as he cast his vote Sunday at a polling station in Ecatepec, the most populous city in the state where he served as mayor before becoming a gubernatorial candidate.

Avila faces Alejandro Encinas, 57, from the leftist Democratic Revolution Party, or PRD, which won the presidential vote in the state of Mexico in 2006 despite PRI domination of state and local offices. Trailing third is Luis Felipe Bravo Mena, 58, of Calderon's conservative National Action Party, or PAN, which won the presidential vote there in 2000.

The PAN and PRD tried early on to form a coalition to defeat the PRI, as they did last year to win the PRI stronghold states of Oaxaca, Puebla and Sinaloa. But the agreement fell apart in Mexico state, and other coalition efforts never got off the ground in two other states, Nayarit and Coahuila, where the PRI is expected to win governorships Sunday.

Across Mexico, many voters are weary of the PAN, which after more than a decade in power has failed to make fundamental changes in Mexico apart from a trademark war on organized crime that has seen a spike in violence. Since President Felipe Calderon took office in late 2006, more than 35,000 people have died in drug violence, according to the government. Other sources put the number at more than 40,000.

And internal fighting in the PRD has left the leftist party in disarray.

The PRI has sprung back in the vacuum.

Euralia Contreras, 66, who voted at the same station as Avila, said that she was sure the PRI would win because it has tackled local problems and helped residents. "I've received many benefits from (Avila)," Contreras said, referring to free canned foods the Avila campaign gave her. "The handouts came through. He has fulfilled his promises."

After mounting one of the most expensive campaigns in Mexico's history, Avila ran tirelessly as a "democrat," polling near 60 percent while Encinas' support has hovered in the mid-to-high 20s in surveys by the newspapers Reforma and El Universal. Those polls have a margin of error of plus or minus 3 percentage points.

The newspaper Reforma reported last month that Avila's campaign spent nearly 4.4 million pesos a day ($376,000), more than the 3.4 million pesos ($290,000) Calderon spent to win the presidency. The campaign didn't respond to questions about spending from the AP.

For Fernando Pasillas Villarreal, there are no good candidates.

"I'll vote, but only to cancel my vote, because I think that although the governor may change, the one who takes his place does not offer substantial improvements, and I still think that the PRI only enriches itself and enriches its friends."

Even as the opposing parties cry foul and have filed complaints with the national elections tribunal over alleged PRI campaign violations, the elections Sunday and next year appear to be the PRI's to lose.

Based on reporting by The Associated Press.

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