Cuba's ailing communist leader, Fidel Castro, has raised the possibility that he may never return to the presidency.
Fidel Castro has not been seen in public for 16 months
In a letter read out on state TV, Mr Castro, Cuba's leader since 1959, said he had a duty not to hold on to power or obstruct the rise of younger people.
Last year, he temporarily handed over power to his brother Raul and has not been seen in public since.
His message comes before elections next year to choose a national assembly which then selects the president.
Reacting to the statement, the White House said it believed democracy would "soon" come to Cuba.
"It's an interesting letter. It's hard to make out what he is saying or what he means," said spokeswoman Dana Perino, quoted by the AFP news agency.
"So we're just continuing to work for democracy on the island and we believe that day will come soon."
Mr Castro's message was delivered during Cuba's main nightly current affairs programme, Mesa Redonda.
"My basic duty is not to cling to office, and even less to obstruct the path of younger people, but to pass on the experiences and ideas whose modest worth stems from the exceptional era in which I have lived," it said.
The BBC's Michael Voss in Havana says there was no indication about how or when the Cuban leader might step down.
Born in 1926 to a wealthy, landowning family
Took up arms in 1953, six years before coming to power
Brother Raul was deputy and Che Guevara third in command
Has outlasted nine American presidents
Target of many CIA assassination plots
Daughter is a dissident exile in Miami
But the mention of younger leaders suggests that his younger brother Raul, who is 76, may not automatically succeed him, our correspondent says.
Fidel Castro has ruled Cuba since leading the 1959 revolution.
Earlier this month he was nominated as a candidate for a seat in Cuba's National Assembly - a move seen as an indication that he might still hope for a return to power.
Mr Castro must be re-elected if he is to remain president of the Council of State, and so head of Cuba's government.
Nationwide elections will be held on 20 January.
The assembly will then choose the Council of State, which President Fidel Castro has headed since the early 1960s.
Mr Castro's illness last year sparked much speculation about the end of one-party rule in Cuba.
But many observers say that there has been a relatively smooth transfer of power.
KEY POLITICAL FIGURES
Felipe Perez Roque, 42: Foreign Minister since 1999, Fidel Castro's protege and former chief of staff
Carlos Lage, 56: Vice President, key economic adviser from early 1990s
Ricardo Alarcon, 70: President of National Assembly. At 18, joined Fidel Castro's revolution, organised youth brigades
BBC Americas editor Emilio San Pedro says the letter appears to be a calculated attempt to prepare Cuba's 11 million people for a Cuba without the emblematic revolutionary leader in charge.
"He has left a solid foundation for us to continue. Even if someone else takes the seat of power, nothing will change," a Havana resident told Reuters news agency.
In Miami, home to many Cuban exiles, there was scepticism about the statement's actual meaning.
Gina Forcellado said she thought the announcement was part of a cynical move by Fidel Castro.
"He knows that he's not going to be judged very well by history, so he's trying to correct it," she told the BBC.
Mr Castro stepped aside after undergoing emergency intestinal surgery in July 2006. His health is a state secret.
Since earlier this year, he has made his presence felt through regular newspaper editorials.
In Monday's message, Mr Castro paid tribute to the Brazilian architect Oscar Niemeyer, a lifelong communist who turned 100 on Saturday.
"I think like Niemeyer that you have to be of consequence up to the end," he wrote.
The comments came in the final paragraph of a letter dealing with this month's climate change conference in Bali.