By Kelly McCleary, Mariano Castillo and Stefano Pozzebon, CNN

(CNN) -- Venezuelans returned to voting booths Sunday for the first major election since July's controversial and deadly vote for a constituent assembly.

This time they're deciding on governorships of the country's 23 states.

Currently government loyalists hold all but three governorships, but observers said there's a chance for the opposition to make gains.

"If the vote were to be completely free and fair, the (opposition) would likely win between 18 and 21 states," according to an analysis by the Eurasia Group, a political risk research and consulting firm.

In the lead-up to election day, the opposition accused electoral authorities of making the ballots confusing and moving polling locations in opposition strongholds in an effort to boost pro-government candidates.

The US State Department condemned Venezuela's National Electoral Council last week, saying its actions call into question "the fairness of the electoral process."

The Venezuelan Electoral Council called the US statement an "aggression perpetrated against our sovereignty," and said changes were made for security reasons.

Concerns that the Electoral Council's changes would sow confusion appeared to have come to fruition Sunday, with many voters unsure about where they were supposed to vote. Long, slow-moving lines greeted voters at polling stations.

Ludmilla Velez Lascar said she was determined to cast her ballot despite her polling location being changed. "Maybe they don't want my vote," Velez Lascar said. "But we have to vote. We have to elect ... our governors."

Venezuelan President Nicolas Máduro called Sunday's vote "a success for Venezuela and the revolutionary democracy, for the socialist democracy."

Last election erupted in violence

Venezuelans headed to the polls Sunday less than three months since the last major vote, when violent clashes erupted between protesters and police, leaving at least six people dead. More than 120 people were killed in months of protest leading up to that vote, the Venezuelan attorney general's office said.

The vote allowed Máduro to establish a new institution called the Constituent Assembly, which was stacked with his supporters. It replaced the National Assembly, which had been controlled by Maduro's opponents.

The new Constituent Assembly gave Máduro the power to rewrite Venezuela's constitution.

In wake of the election, London-based Smartmatic -- which provided the voting technology -- said turnout figures were manipulated.

The US Treasury Department called the July election "illegitimate" and slapped new sanctions on Maduro.

The-CNN-Wire

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