Such fears have been fueled by President Maduro telling his supporters that “we will win, no matter what.”
But President Maduro vowed after voting in the capital on Sunday that he would “make sure” the result is respected, according to AFP.
According to Reuters, Venezuelans began casting their ballots at 6 a.m. local time (10 a.m. GMT), before voting was scheduled to begin.
The agency added that tensions were high outside one polling station in Caracas, with voters in line clashing with each other as they waited for the doors to open.
The number of independent election observers monitoring the vote in the country is very limited: four from the United Nations and a small technical team from the Carter Center.
The head of the electoral commission, a close ally of President Maduro, has rescinded an invitation to the European Union watchdog to attend.
Former Argentine President Alberto Fernández was also not invited after saying the Maduro government must accept the possibility of losing the election.
But President Maduro welcomed hundreds of guests from countries allied with his government and said they would “accompany” him to the vote.
The opposition mobilized thousands of people to act as witnesses at individual polling stations.
The opposition has faced many challenges, including constant harassment and the arrest of more than 100 people involved in the campaign since the beginning of the year, but it is optimistic.
Opinion polls show his country's candidate with a huge lead over President Maduro, making it impossible for him to “steal the election”.
The government dismissed opinion polls cited by the opposition, insisting its candidate was leading.
President Maduro himself has been vocal in his rhetoric ahead of the election, warning of a “sea of blood” if he loses.
The remarks prompted Brazil's leftist leader Luiz Inácio Lula da Silva to criticize Maduro, saying he must learn a lesson: “If you win, you stay in power, but if you lose, you step down.”
President Maduro has used the image of a fighting rooster as a symbol of his campaign, creating an aggressive tone.
