The main opposition party in Mexico is expected to make sweeping gains in elections for new governors and mayors in around a third of the country.
The Institutional Revolutionary Party or PRI is tipped to win most of the 12 polls, keeping many of the nine governorships it currently controls and pushing out rivals in some of the other three.
A big PRI victory could launch Enrique Pena Nieto, the governor of the state of Mexico, next to Mexico city and his bid to take the presidency in 2012.
Security was tight after a particularly violent campaign believed to have been orchestrated by drug gangs.
Last week, one of the country’s most popular politicians, Rodolfo Torre as was ambushed and killed along with four of his aides. It was Mexico’s highest-profile political murder in 16 years.
The upsurge in drug related killings along with a feeble economy has undermined the ruling conservatives’ popularity. With the left divided and President Felipe Calderon sinking in opinion polls, the PRI is set for a come-back after being ousted in 2000.