César Cielo, who is yet to qualify for the Games, is the most successful Brazilian swimmer in history, having won 50 metres freestyle gold and 100m freestyle bronze at Beijing 2008 before 50m freestyle bronze at London 2012.

He gained 19 per cent of a vote in a survey of the Rio de Janeiro population undertaken by the University Center Research Laboratory Practices UniCarioca.

If successful, the 28-year-old would become the first Brazilian swimmer to carry the flag at his home Games, following the likes of showjumper Rodrigo Pessoa, who did so at London 2012 and sailors Robert Scheidt and Torben Grael, who did so at Beijing 2008 and Athens 2004 respectively.

César Cielo has also won six long-course and five short-course titles at various editions of the World Championships, as well as seven gold medals at the Pan American Games.

In 2011, the 28-year-old tested positive for banned diuretic and masking agent furosemide before being allowed to return to competition after the Court of Arbitration for Sport upheld his claim that it was due to a contaminated batch of a food supplement he regularly used.

This came after the International Swimming Federation had appealed for a stiffer punishment than the warning initially issued by the Brazilian Swimming Federation.

London 2012 rings gold medallist Arthur Zanetti finished second, with 14 per cent support.

Retired volleyball legend Giba, who followed gold in Athens with silvers in Beijing and London before bowing out of the sport in 2014, came third with 11 per cent even though he is not planning to compete in Rio.

Football superstar Neymar attracted eight per cent of the vote, while 2011 pole vault world champion Fabiana Murer took seven per cent and London 2012 under 48 kilograms judo gold medal winner Sarah Menezes recorded three per cent. 

The research, which involved 1,144 people in Rio last month, also found that Jamaica's sprint sensation Usain Bolt, the six-time Olympic gold medallist, was the foreign athlete Brazilians were most excited to see this summer.

He received 41 per cent of the vote, ahead of American swimmer Michael Phelps, the most decorated Olympian of all time who recorded eight per cent and Spanish tennis player Rafael Nadal with seven per cent. 

The Brazilian flagbearer is not expected to be chosen until shortly before the Games.