Venezuelan President Nicolas Maduro casts his vote during the presidential elections in Caracas, Venezuela, on May 20, 2018 (Xinhua/Boris Vergara)

CARACAS, May 20 (Xinhua) -- Venezuelans went to the polls on Sunday in presidential elections.

"I call on all Venezuelans to exercise their right to vote," President Nicolas Maduro made the call in an afternoon address at the government headquarters in Caracas.

"The will of the Venezuelan people will be respected here and around the world," said Maduro, referring to voting centers set up abroad for citizens residing in foreign countries.

Surveys showed that Maduro, who is running for reelection to a second six-year term, has been leading voter preferences.

Some 14,638 voting centers have been set up nationwide for Venezuela's more than 20.5 million eligible voters, who are also voting for state legislators.

Voting is progressing with "absolute normality," Interior and Justice Minister Nestor Reverol told reporters early in the day as he was leaving his local voting station in the capital.

Henri Falcon, one of the opposition candidates, also called on his supporters to get out and vote as he cast his ballot in the west-central state of Lara.

"This is not the time to twiddle your thumbs," said Falcon, using an expression that means to stand idly by and do nothing.

Some 150 international observers from 30 countries and international organizations are in Venezuela for the elections, including former Ecuadorian President Rafael Correa, the online daily Noticias24 said.