Mexico elections: President's party set to retain power
In Mexico's elections for Congress, President Enrique Pena Nieto's Institutional Revolutionary Party and its allies look set to retain control.
On current projections, the PRI will win around 30% of the vote and see its number of seats drop slightly.
An independent candidate has won a state governorship for the first time since legal change allowed that.
The run-up to the poll was marked by violence with drug cartels blamed for the deaths of several candidates.
The head of the National Electoral Institute, Lorenzo Cordova, said that the president's party and its allies look set to win between 246 and 263 seats in the 500-member lower chamber.
The opposition conservative National Action Party has won around 22% of the vote, he said.
The government suffered some setbacks. It lost the governorship of the northern state of Nuevo Leon to an independent, Jaime Rodriguez Calderon.
The outspoken rancher, also known as "El Bronco" or the gruff one, is the first independent to win a state governorship.
His victory is seen as a wake-up call for the country's traditional parties, says the BBC's Katy Watson in Mexico City.
As voting got under way on Sunday, a dissident teachers' union burned ballots and ransacked offices of political parties in the south of the country to express its anger at the president's proposed education reforms.
Election materials were also burned by protesters in the town of Tixtla, where 43 trainee teachers are believed to have been killed last year after police handed them over to drug gangs.
Analysis by Katy Watson, BBC News, Mexico City
Ahead of the elections, there was a great deal of pessimism - the feeling among many that votes do not really matter, politicians here are all the same, and violence will continue no matter what.
But at a polling station on Sunday, in relatively peaceful Mexico City, there was a sense of duty among many - that voting was the only way to make a difference. Asked what their main concern was and almost without exception, the response among voters was: 'Security.' People here are worried about where the country is heading.
Despite President Pena Nieto's promises to restore peace in Mexico, these elections have proved otherwise. They have been some of the most violent in recent history.
Ahead of the polls opening, the CNTE teachers' union attacked the offices of five political parties in Chiapas state in the south of the country.
In Guerrero state, explosive devices were thrown into a conservative party's office.
Meanwhile in Oaxaca, as well as Guerrero, tens of thousands of ballot papers were burnt by protesters.
A former mayor was shot dead outside a polling station in the same state.