Ricardo Alarcón de Quesada, 75, one of Cuba’s longest-serving officials and a specialist on U.S. relations, will leave the post of president of the National Assembly of People’s Power in February after 20 years on the job.

The Cuban government made no comment on the departure, but Alarcón’s name was not on the list of the 612 candidates in the upcoming elections for the legislative body published in the official newspaper Granma Thursday.

Although Alarcón remains a member of the Cuban Communist Party’s powerful Political Bureau, speculation that he was in disfavor has mounted since police arrested top aide Miguel Alvarez last summer on suspicion of corruption and spying.

He has sometimes been described as the third-ranking official in Cuba after Raúl and Fidel Castro. He is known as a skillful foreign policy operator with a specialty in the long-hostile relations between Cuba and the United States.

Alarcón served as ambassador to the United Nations for two terms totaling about 20 years, as foreign minister from 1992 to 1993 and since then as president of the legislature, which meets for only a few days per year. Most laws are approved by decree.

In 1994, he headed the five-member Cuban delegation that negotiated a migration agreement with the Clinton administration following the “Rafter Crisis” that saw more than 35,000 Cubans leave the island in makeshift vessels.

Miami radio commentator Max Lesnik reported Wednesday that he had unconfirmed reports Alarcón would leave the post of assembly president to “focus” on the campaign for the release of five Cuban spies convicted in a Miami trial.

Lesnik, a close friend of Alarcón, speculated he will be succeeded by Esteban Lazo, a Politburo member, vice president of the government’s top Council of State and a candidate in the Feb. 3 election for the next National Assembly.

Another possible candidate to replace the assembly president may be Ana Maria Mari Machado, only appointed as vice president of the legislature in July.

Asked whether Alarcón’s departure was the result of the arrests of Alvarez and his wife, Mercedes Arce, both identified as former intelligence agents, Lesnik said, “I really don’t see a relationship between one thing and another.”

Alvarez and Arce have been detained in Havana since March 3 for investigation, initially on charges of corruption but later for espionage, according to a close colleague who believes they were targeted in order to get at Alarcón.

Arce, an academic and part-time resident of Mexico, is suspected of obtaining sensitive Cuban information through her husband and using it in “business reports” sold to foreigners, according to one source. Former FIU professor Carlos Alvarez, convicted of spying for Cuba, identified Arce as one of his handlers in the 1980s and 1990s.

Miguel Alvarez, who is not related to the FIU professor, was senior advisor to Alarcón on international and political affairs. Cuba’s state-run media has not reported on the case.

Alarcón, a lawyer who graduated from the University of Havana, was active in the urban wing of the Castro guerrillas that toppled Fulgencio Batista in 1959. While at the U.N. he served one-year terms as president of the Security Council and vice president of the General Assembly, and perfected his command of English.

He was elected to the Central Committee of the Communist Party in 1980 and in 1992 to the Politburo, the party’s top standing body. Cuban ruler Raúl Castro has been putting allies and younger people in top jobs since he succeeded brother Fidel in 2008, but there are older candidates than Alarcón who are standing for election.

Among them are: Fidel Castro, 86; Raúl Castro, 82; José Ramón Fernández, 90; Guillermo Garcia, 87; Armando Hart Dávalos, 83; and Jose Ramon Machado Ventura, 82. Esteban Lazo himself is 68.

The Granma list also included, for the first time, Mariela Castro Espín, the daughter of Raúl Castro. She is head of the National Center for Sex Education and a gay rights activist.

The new deputies are expected to gather for their first session on Feb. 24 to elect a new assembly president and then elect Raúl Castro to a second five-year term as president of the Councils of State and Ministers.