Fidel Castro
© The Associated Press/Javier Galeano
In this Sept. 28, 2010, file photo, Cuba's leader Fidel Castro delivers a speech during the 50th anniversary of the Committee for the Defense of the Revolution, CDR, in Havana, Cuba. Castro said Tuesday, March 22, 2011, he resigned five years ago from all his official positions, including head of Cuba's Communist Party, a position he was thought to still hold.
Fidel Castro's surprise announcement that he stepped down as head of the Communist Party five years ago - despite widespread belief he remained in charge - marks the bizarre end of an era for a nation, and a man, whose fates have been intertwined for more than half a century.

The 84-year-old revolutionary icon made the revelation Tuesday - with word of the resignation thrown in as an aside halfway through an opinion piece that otherwise focused on President Barack Obama.

The declaration raises fundamental questions about just how much power Fidel has been wielding behind the scenes since his 2006 illness, and to what extent his 79-year-old brother has had freedom to make his own decisions as he pushed the country to enact sweeping economic reforms.

It also gives the Castros an opportunity to tap a possible future successor with their naming of a new party No. 2 - one without their famous last name.

They might select from a cadre of younger leaders who could carry the fiscal changes forward, and perhaps even reboot relations with the United States. Alternatively, the brothers could look to the past by promoting a loyal-but-weathered veteran of the revolution that brought them to power in 1959.

The answer will likely become apparent through a high-level game of musical chairs that Fidel's departure will engender in the upper reaches of the Communist Party hierarchy during a crucial Communist Party Congress next month.

In Tuesday's opinion piece, Castro said that when he got sick in 2006, "I resigned without hesitation from my state and political positions, including first secretary of the party ... and I never tried to exercise those roles again."

He said that even when his health began to improve, he stayed out of state and party affairs "even though everyone, affectionately, continued to refer to me by the same titles."

In the opinion piece, Fidel indicated that, with or without formal titles, he will always be an intellectual force in the revolution, a refrain he has uttered several times in recent years.

"I remain and will remain as I have promised: a soldier of ideas, as long as I can think and breathe," he writes.

The article, which was published on the state-run Cubadebate website overnight and in newspapers Tuesday morning, caught many people by surprise.

"It's incredible. Nobody can believe it," said Magaly Delgado, a 72-year-old Havana retiree who was clutching a copy of Granma, the Communist Party daily. "I always thought he was still in charge. ... He never said he had resigned."

The Cuban government had no immediate comment on the revelation, which appeared to tweak history. Fidel stepped down in 2006 due to a serious illness that almost killed him. In an official proclamation released on July 31, 2006, he provisionally delegated most of his official duties to his brother - including the presidency and head of the party.

In February 2008 he announced he was officially stepping down as president, and Raul Castro was formally picked to succeed him by the country's parliament a few days later. But no reference was made to Fidel leaving his party post, and Cuban officials and ordinary people have referred to him as the party leader ever since.

Even after the announcement, the Communist Party website on Tuesday listed Fidel as first secretary, with Raul as second secretary.

It is widely expected that Raul will formally be named to the top spot at the April congress, and analysts say the choice of second secretary will say a lot about how the brothers envision a transition to an eventual post-Castro era.

"They could send a startling message by picking somebody young or out of the party, or somebody whose name is not easily recognized," said Robert Pastor, a professor at American University and longtime adviser on hemispheric affairs. "Most people would guess, however, that they will pick ... an octogenarian who fought in the revolution."

While the government historically has focused on the day-to-day running of the country, the party is tasked with guiding the Cuban people on their path to communism. In practice, no major policy can be passed without the party first agreeing.

There are a scattering of young leaders including Lazaro Exposito, the fast-charging Communist Party chief in Santiago de Cuba, and Lazara Lopez Acea, the 47-year-old top party leader for Havana, as well as Bruno Rodriguez, the 53-year-old foreign minister, and Marino Murillo, the 50-year-old economy minister.

But none appears ready to step into such a high-profile role, and neither Fidel nor Raul has ever indicated publicly that one is favored over the others. Since taking office, Raul has also elevated a number of generals to high-ranking jobs at state-run entities, but they are technocrats largely unknown to the public.

Some young politicians might be reluctant to step into such a senior position, conscious that the career path of those who have flown too high, too fast, has usually been short. In 2009, Raul suddenly fired two of the island's rising political stars: Foreign Minister Felipe Perez Roque, then 43, and Vice President Carlos Lage, who at 57 was relatively youthful given the advanced ages of most government officials. Both were captured on a secret video tape drinking whiskey and joking about the country's old leaders.

"The truth is Raul's experience with young leaders hasn't been very good these past few years, so I think he will name a historic figure," said Eduardo Bueno, a professor of international relations at Mexico's Iberoamerican University. "That said, if the younger generation could take a step forward it would be a great signal, including for Raul, that things are finally moving and the country's long paralysis is over."

The safest choice for the No. 2 party spot would probably be Jose Ramon Machado Ventura, a strict disciplinarian of unquestioned loyalty who has been with the Castros since their guerrilla days in the Sierra Maestra mountains and once extracted a bullet from Argentine revolutionary Ernesto 'Che' Guevara's foot.

Machado Ventura, 80, is already Raul Castro's first vice president and holds several other key posts in the government.

Another old-timer who could get the nod is Ramiro Valdes, 78, who is vice president of Cuba's supreme governing body, the Council of State, and oversees the crucial ministries of telecommunications and construction from a new position carved out for him in January.

But neither choice is likely to shake things up politically, or result in improved relations with the United States, which has maintained an economic embargo on Cuba for 48 years.

Bilateral ties have plunged into a deep freeze recently due to the conviction earlier this month of U.S. contractor Alan Gross, who received a 15-year prison sentence for bringing satellite equipment into the country illegally.

A congressional staffer involved in U.S.-Cuba relations said Fidel's official departure from the party will not lead, at least in the short term, to improved relations with Washington.

"It will not have much of a political impact on bilateral relations because Raul has the same last name," he said, speaking on condition of anonymity because he was not authorized to discuss the matter publicly. He said it would take the death of one or both of the two brothers to change perceptions in the United States.

"His stepping down will be a watershed on the island, for sure, and it will be seen as such by most in Washington," he said. "But some people will still say Fidel is calling the shots, whether or not it is really the truth anymore."

However the party shake-up plays out, it is likely to leave Raul with more room to transform the island's ever-weak economy.

The Communist Party Congress at which Fidel's successor is likely to be picked has been called to set a new economic path for the country, one which Raul has been pushing since he took office.

Many of the changes Raul has already embraced, like allowing Cubans to go into business for themselves, rent homes and even hire employees, have long been anathema to his brother.

There has been speculation - impossible to confirm in Cuba's hermetically sealed political culture - that Raul Castro would have moved the reforms along faster if not for his older brother's larger-than-life presence and continued influence behind the scenes.

Tomas Bilbao, the executive director of the Washington-based nonprofit Cuba Study Group, which supports increasing economic and academic exchanges with the island, said the impact of Fidel's resignation cannot be overstated.

"I think it's significant because if nothing else it's Fidel Castro sending a clear message that his brother is in charge of the country," he said. "It's a big boost in credibility for Raul and the reforms he's trying to push."