Caracas, Venezuela (CNN) Venezuela's political opposition denounced the results of Sunday's regional elections, after President Nicolas Máduro claimed victory.

The regional elections held Sunday had 23 gubernatorial seats up for grabs. It was the first major election since July's controversial and deadly vote for a constituent assembly, and is also the country's first contested election since December of 2015.

With 95.8% of the votes counted, Venezuela's National Electoral Council said that Máduro's party was favored in 17 states and the opposition coalition Mesa de la Unidad Democrática (MUD) in five. The outcome in the remaining state was not yet clear, it said in a statement.

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

But opposition politician Gerardo Blyde early Monday demanded a complete audit on all of Sunday's results.

Blyde, a campaign coordinator of the opposition coalition MUD, has called for street protests later Monday.

Before the vote, government loyalists held all but three governorships, but observers had said there was 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 a pre-election analysis by the Eurasia Group, a political risk research and consulting firm.

Vzlans hit the polls to elect State governors amid chaos on candidates, voting centres.. flier tells u exactly what to cross #ThisIsVzla pic.twitter.com/dDf8LzbIBI — stefano pozzebon (@StePozzebon) October 15, 2017

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.

My day so far.. #regionales2017 #ThisIsVzla #newToys A post shared by Stefano Pozzebon (@stepozzebon) on Oct 15, 2017 at 7:42am PDT

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."

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.

Photos: Crisis in Venezuela A costumed demonstrator in Caracas, Venezuela, protests the government of Venezuelan President Nicolas Maduro on Sunday, August 6. Unrest continued to sweep through the country after a new legislative assembly was inaugurated following a controversial election on July 30. The new assembly has wide-ranging powers and is expected to rewrite the Venezuelan constitution at Maduro's behest. Opposition supporters, who see the vote as a power grab and an erosion of democracy, boycotted and staged demonstrations against the vote. Hide Caption 1 of 49 Photos: Crisis in Venezuela Soldiers stop a vehicle and detain its passengers on the Paramacay military base in Valencia, Venezuela, on August 6. According to authorities, two people were killed when an anti-government paramilitary attack was quelled at the base. Hide Caption 2 of 49 Photos: Crisis in Venezuela Anti-government activists stand near a flaming barricade in Valencia on August 6. Hide Caption 3 of 49 Photos: Crisis in Venezuela A man is arrested in Valencia during clashes between anti-government activists and the National Guard on August 6. Hide Caption 4 of 49 Photos: Crisis in Venezuela Members of the Venezuelan armed forces fly over Valencia in a helicopter while citizens demonstrate in support of a group that staged a paramilitary uprising at the Paramacay military base on August 6. Hide Caption 5 of 49 Photos: Crisis in Venezuela Venezuela's Chief Prosecutor Luisa Ortega Diaz, third from left, is surrounded by employees of the General Prosecutor's office as she is barred by security forces from entering her office in Caracas on Saturday, August 5. Hide Caption 6 of 49 Photos: Crisis in Venezuela Diosdado Cabello, a member of Venezuela's National Constituent Assembly, holds an image of Venezuela's late President Hugo Chavez as delegates gather for a group photo following their swearing-in ceremony on Friday, August 4. Hide Caption 7 of 49 Photos: Crisis in Venezuela Opposition activists protest against the newly inaugurated National Constituent Assembly on August 4. Hide Caption 8 of 49 Photos: Crisis in Venezuela A woman in Caracas attends a vigil Monday, July 31, for anti-government activists who have died in the country's recent unrest. More than 120 people have been killed in Venezuela since early April, according to the attorney general's office. Hide Caption 9 of 49 Photos: Crisis in Venezuela Opposition lawmaker Juan Requesens addresses a rally in Caracas on July 31. Two other leading opposition figures, Leopoldo Lopez and Antonio Ledezma, were rounded up from their homes, according to their families. Hide Caption 10 of 49 Photos: Crisis in Venezuela Maduro celebrates the results of a national vote on Sunday, July 30. His opponents boycotted the election and demonstrated against it for weeks, saying he orchestrated it to get around the existing National Assembly, which the opposition has controlled since 2015. Maduro has argued that the Constituent Assembly will help bring peace to a polarized country, with all branches of the government falling under the political movement founded by his late mentor and predecessor, Hugo Chavez. Hide Caption 11 of 49 Photos: Crisis in Venezuela Members of Venezuela's national police are caught in an explosion as they ride motorcycles near Altamira Square in Caracas on July 30. Venezuela has seen widespread unrest since March 29, when the Supreme Court dissolved Parliament and transferred all legislative powers to itself. The decision was later reversed, but protests have continued across the country, which is also in the midst of an economic crisis. Hide Caption 12 of 49 Photos: Crisis in Venezuela A wounded anti-government demonstrator is helped by medics during clashes with police in Caracas on July 30. Hide Caption 13 of 49 Photos: Crisis in Venezuela A demonstrator shouts slogans through a traffic cone during an anti-government protest in Caracas on July 30. Hide Caption 14 of 49 Photos: Crisis in Venezuela A protester wounded by a pellet gun receives attention July 30 during a demonstration against the vote for a Constituent Assembly. Hide Caption 15 of 49 Photos: Crisis in Venezuela A member of the National Guard fires at protesters during clashes in Caracas on Friday, July 28. Hide Caption 16 of 49 Photos: Crisis in Venezuela A demonstrator dressed as Venezuelan independence hero Simon Bolivar is silhouetted against a national flag in Caracas on Monday, July 24. Hide Caption 17 of 49 Photos: Crisis in Venezuela Venezuelan police Officer Oscar Perez joins in an anti-government protest in Caracas on Thursday, July 13. Perez allegedly piloted a stolen police helicopter used to attack the Venezuelan Supreme Court with grenades on June 27. Hide Caption 18 of 49 Photos: Crisis in Venezuela Venezuelan lawmakers Luis Stefanelli, left, and Jose Regnault appear stunned in a corridor of the National Assembly after a clash with demonstrators in Caracas on Wednesday, July 5. Supporters of Maduro stormed the building and attacked opposition lawmakers, witnesses said. At least seven legislative employees and five lawmakers were injured, according to National Assembly President Julio Borges. Journalists said they were also assaulted. Hide Caption 19 of 49 Photos: Crisis in Venezuela National Guard members clash with deputies of the National Assembly in the Parliament's courtyard in Caracas on Tuesday, June 27. Hide Caption 20 of 49 Photos: Crisis in Venezuela A boy runs under a national flag during a June 27 protest in Caracas. Hide Caption 21 of 49 Photos: Crisis in Venezuela Protesters tear down a fence at the La Carlota airbase outside Caracas on Friday, June 23. A soldier shot a demonstrator through the fence at the base on the previous day, killing him. Hide Caption 22 of 49 Photos: Crisis in Venezuela Hide Caption 23 of 49 Photos: Crisis in Venezuela Protester David Jose Vallenilla is shot through a fence by a member of the National Guard near a military base in Caracas on Thursday, June 22. Vallenilla later died in the hospital after suffering three gunshot wounds to the chest. Hide Caption 24 of 49 Photos: Crisis in Venezuela Maduro holds up a copy of the Venezuelan constitution during a news conference at the presidential palace in Caracas on June 22. Maduro has called for changes to the constitution amid the unrest. Hide Caption 25 of 49 Photos: Crisis in Venezuela A protester hides behind a barrier in Caracas on June 22. Hide Caption 26 of 49 Photos: Crisis in Venezuela An opposition activist displays bullet shells during an anti-government demonstration on Monday, June 19. Hide Caption 27 of 49 Photos: Crisis in Venezuela People flee during a clash between opposition demonstrators and riot police in Caracas on June 19. Hide Caption 28 of 49 Photos: Crisis in Venezuela Opposition activists aim projectiles toward riot police during a demonstration on June 19. Hide Caption 29 of 49 Photos: Crisis in Venezuela Demonstrators stand in front of a police vehicle on June 19. Hide Caption 30 of 49 Photos: Crisis in Venezuela A street in eastern Caracas is painted with the names of people killed during more than two months of protests. Hide Caption 31 of 49 Photos: Crisis in Venezuela During a "Grandparents' March" in Caracas, a man is blocked by police from reaching the Government Ombudsman's Office on Friday, May 12. Hide Caption 32 of 49 Photos: Crisis in Venezuela Opposition activists scuffle with riot police in Caracas on May 12. Hide Caption 33 of 49 Photos: Crisis in Venezuela Thousands of Venezuelan protesters march on a Caracas highway on Wednesday, May 10. Hide Caption 34 of 49 Photos: Crisis in Venezuela Opposition activists clash with riot police in Caracas on Monday, May 8. Hide Caption 35 of 49 Photos: Crisis in Venezuela Hide Caption 36 of 49 Photos: Crisis in Venezuela An armored National Guard vehicle runs over a protester in Caracas on Wednesday, May 3. The protester, 22-year-old Pedro Michell Yaminne, survived, his mother told CNN. Interior and justice minister Nestor Reverol told reporters that the "lamentable" incident was under investigation. He said that moments before Yaminne was run over, demonstrators hurled a Molotov cocktail at the armored vehicle, opened the side door and "brutally assaulted" the driver. Hide Caption 37 of 49 Photos: Crisis in Venezuela A demonstrator catches fire during protests in Caracas on May 3. It happened as protesters clashed with police and the gas tank of a police motorcycle exploded. Other photos from the scene showed the man being attended for burns to his body. Hide Caption 38 of 49 Photos: Crisis in Venezuela A demonstrator stands in front of an armored vehicle during protests in Caracas on Wednesday, April 19. Hide Caption 39 of 49 Photos: Crisis in Venezuela Opposition leader Henrique Capriles reacts to tear gas during a protest on April 19. Hide Caption 40 of 49 Photos: Crisis in Venezuela Riot police clash with demonstrators while tear gas fills the air in Caracas on April 19. Hide Caption 41 of 49 Photos: Crisis in Venezuela Rescue workers tend to a demonstrator hit by a tear gas canister during anti-government protests on April 19. Hide Caption 42 of 49 Photos: Crisis in Venezuela A demonstrator reacts during a march in Caracas on Saturday, April 15. Hide Caption 43 of 49 Photos: Crisis in Venezuela A protester suffering from the effects of tear gas is carried away on Thursday, April 13. Hide Caption 44 of 49 Photos: Crisis in Venezuela Clouds of tear gas spread across a highway in Caracas during clashes on Monday, April 10. Hide Caption 45 of 49 Photos: Crisis in Venezuela Demonstrators help a journalist whose leg was injured while covering clashes in Caracas on April 10. Hide Caption 46 of 49 Photos: Crisis in Venezuela Thousands of demonstrators protest against Maduro in Caracas on Saturday, April 8. Hide Caption 47 of 49 Photos: Crisis in Venezuela Venezuelan police line up before clashing with opposition activists on Thursday, April 6. Hide Caption 48 of 49 Photos: Crisis in Venezuela Demonstrators fight with national police officers in Caracas on Tuesday, April 4. Hide Caption 49 of 49

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