Venezuelans go to the polls on Sunday against a backdrop of hope and fear in a presidential election that could end 25 years of socialist rule – if a free and fair vote is allowed.

Opinion polls suggest that the president Nicolás Maduro, 61, who is seeking his third term, could be defeated by the opposition coalition candidate, retired diplomat Edmundo González Urrutia, 74.

But experts warn that it is one thing for González to gain more votes, and another is for him to be announced as winner by the National Electoral Council, which is aligned with Maduro’s government.

Independent observers describe this election as the most arbitrary in recent years, even by the standards of an authoritarian regime that started with Maduro’s predecessor, Hugo Chávez.