Fidel Castro said Friday that he's relieved to be stepping down as Cuba's president, complaining that the process of selecting Cuba's next government "had left me exhausted."

After nearly a half-century in power, Castro announced Tuesday that he wouldn't accept another term when parliament selects a new government on Sunday.

"The night before, I slept better than ever," Castro wrote in a newspaper column. "My conscience was clear and I promised myself a vacation."

The ailing 81-year-old said Tuesday that he's not well enough to continue as president. Most expect his brother Raul, five years younger, to step into the presidency on Sunday. Raul Castro has been acting president since his brother fell ill in July 2006.

Fidel Castro said he had planned on taking a break from his newspaper columns for at least 10 days, but decided: "I didn't have the right to keep silent for so long."

The column published Friday in both major government-controlled newspapers focused on the United States, with Castro poking fun at U.S. presidential candidates. He said word of his retirement forced them to talk about Cuba.

"I enjoyed observing the embarrassing position of all the presidential candidates in the United States," he wrote. "One by one, they could be seen forced to proclaim their immediate demands to Cuba so as not to alienate a single voter."

He criticized demands by the candidates and by U.S. President George W. Bush for political change on the island.

"'Change, change, change!' they shouted in unison. I agree. 'Change!' But in the United States," he wrote. "Cuba changed a while ago and will continue on its dialectical course."

He added of Bush: "'Annexation, annexation, annexation!' the adversary responds. That's what he thinks, deep inside, when he talks about change."

Castro asked press authorities not to run the column on page one, and the column was printed on page four of both newspapers. That's in contrast to the front-page play given to Castro's earlier columns written before his resignation.

He titled the column "Reflections of Companion Fidel," rather than "Reflections of the Commander in Chief," which he had used earlier. State Web sites that ran the column changed the logo as well, replacing an image of Castro in olive-green fatigues with one of the leader half-smiling, his hand thrust high in a wave.

Castro remains head of the Communist Party, the only political faction tolerated in Cuba.