Alastair Fox, the head of competitions for the governing body ISAF, said sailing officials had become "frustrated with it all" after seeing little done to clean the bay of raw sewage and floating debris.
"If we have to race all the races outside the bay, if that's what it comes to, to ensure a fair regatta, then that's something we're going to explore and could do," Fox said in a telephone interview.
Fox said two sailing courses located just outside the bay in the open Atlantic — and a third being planned there — could be used for all races. Three other courses have been planned inside the bay, but may not be used.
Fox said the ISAF had asked the Switzerland-based International Olympic Committee to pressure Brazilian politicians. He said the local organizing committee was not at fault, putting the blame on the government.
"We are going to review the situation and make some more recommendations — demands is probably the right word — to make sure things are done," Fox said.
Rio officials promised to clean the bay as part of their campaign in winning the bid in 2009. But as with last year's World Cup in Brazil, not all large promises may be kept.
Over the last year, officials of the Rio state government have claimed progress in Guanabara, only to be contradicted by scientists who study the bay's ecology. In February IOC officials assessing Rio's preparations said they were hopeful pledges to clean the bay would be kept.
But shortly after IOC officials left town, Rio Mayor Eduardo Paes in a television interview called the Guanabara cleanup "a lost opportunity."
"It is a pity that the Olympics, in this case, won't be the reason to solve the pollution issue once and for all," Paes said.
Guanabara presents two problems for sailors.
First, untreated sewage is a health risk. Second, rubbish that washes into the bay from the city's hilltop favelas, or slums, could stop races, foul rudders and cause the loss of an Olympic gold medal.
"The bottom line is we've got to have a fair Olympics," Fox said, "and make sure that our sailors are not at risk from health problems and there is fair racing."
Several months ago, a drug-resistant "super bacteria," normally found in hospitals and difficult to treat, was discovered in the water in a river feeding into the bay.
"We knew we would need patience with this," Fox said. "But I think a lot of people are surprised it has taken this long and we're still not really sure how much they will be able to do."
Fox said a test event in August would be critical. He said he expected many sailors to arrive in Rio beginning in November and stay through May to test the courses.
Other waters around Rio are also polluted.
Earlier this month, at least 37 tons of dead fish were dredged from Rio's Rodrigo de Freitas lake in the heart of Rio. This is the venue for rowing and canoeing.
Rio environmental officials said the die-off was caused by a sudden change in water temperature. However, several scientists told The Associated Press that pollution was to blame.
In a statement to AP, the world governing body of rowing, FISA, said it would "continue to monitor the situation closely" but was it was "confident that our athletes will be pleased with the venue."
Stephen Wade on Twitter: http://twitter.com/StephenWadeAP