MEXICO CITY (AP) — Mexico's ruling party has lost seats in congress but may gain a majority from its coalition with the small but growing Green Party that was everywhere during the campaign, according to official voting trends released late Sunday by the electoral institute.
Voters also elected Mexico's first independent governor after a reform allowing unaffiliated candidates, a move seen as a jolt to all political parties.
Independent Jaime Rodriguez, known as "El Bronco," had at least a 6-point lead in the race in Nuevo Leon state, according to exit polls conducted by the television network TV Azteca and other media.
The margin of error in the Azteca survey, however, was 3.8 percentage points. The ruling party candidate, Ivonne Alvarez, acknowledged the vote was close.
Rodriguez's popularity in a state that is home to the business hub of Monterrey was attributed to voters' disgust with all political parties, each with its own corruption scandals.
"Nuevo Leon has shown that through the ballot box, you can change things," Rodriguez said in addressing his supporters, adding that he will wait for the official count to confirm his victory. "We're going to give the parties six years of vacation."
His support harkens back to 2000, when another plainspoken cowboy candidate, Vicente Fox, managed to topple the PRI's 71-year rule and win the presidency for the opposition National Action Party.
The voting, marred by sporadic outbursts of violence, was seen as a litmus test for President Enrique Pena Nieto and his Institutional Revolutionary Party.
The PRI lost seats, according to the official early count. But a surge in Green Party representatives, from 27 in the current congress to as many as 48, could give the PRI-Green coalition 251 of 500 votes, a majority the party has lacked until now.
Protesters burned ballot boxes in several restive states of southern Mexico in an attempt to disrupt elections, but officials said the vote was proceeding satisfactorily despite "isolated incidents."
"Considering the challenges we faced in this election, the balance has been positive," electoral institute head Lorenzo Cordova said in a national address after polls closed.
Thousands of soldiers and federal police guarded polling stations where violence and calls for boycotts threatened to mar elections for 500 seats in the lower house of Congress, nine of 31 governorships and hundreds of mayors and local officials.
The elections drew a turnout of between 47 and 48 percent, the electoral institute said.
Midterm elections usually draw light turnout, but attention was unusually high this time as a loose coalition of radical teachers' unions and activists vowed to block the vote.
The teachers' demands include wage hikes, an end to teacher testing and the safe return of 42 missing students from a radical teachers' college. Those students disappeared in September, and prosecutors say they were killed and incinerated by a drug gang.
Protesters burned at least seven ballot boxes and election materials in Tixtla, the Guerrero state town where the teachers' college is located.
Soon after, there was an exchange of rock-throwing between protesters and hundreds of people who said they intended to defend their right to vote. There were no immediate reports of injuries.
Ballot boxes were also destroyed in the southern states of Chiapas and Oaxaca. In Oaxaca's capital, masked protesters emptied a vehicle of ballots, boxes and voting tables and burned the material in the main square.
The state government reported 88 arrests related to the destruction of election materials and disturbances in the capital, Tuxtepec and Salina Cruz.
In Monterrey, two political parties reported that armed men were intimidating voters in three towns near the border with Texas.
Interior Secretary Miguel Angel Osorio Chong called it the "most watched-over" vote in Mexican history and said there were only "minimal" problems so far.
"That is good for all of us, to be able to carry out a calm process in which citizens may determine their next leaders and for that to be something normal," Osorio Chong said.
Mexico's National Electoral Institute reported that nearly 100 percent of polling places were able to open.
Among the most volatile states is Guerrero, where at least 10 people died in a clash between community self-policing groups Saturday, but it did not appear to be linked to the election.
Some cast blank ballots as a protest against a political class they consider corrupt and ineffective.
Violence ahead of the elections has already claimed the lives of three candidates, one would-be candidate and at least a dozen campaign workers or activists.
Associated Press journalists Jose Maria Alvarez and Jose Antonio Rivera in Tixtla, Mark Stevenson in Oaxaca and Christopher Sherman, Maria Verza and Peter Orsi in Mexico City contributed.