Factbox: Allies of Venezuela's President Hugo Chavez

(Reuters) - Doubts about the health of Venezuelan President Hugo Chavez after surgery have focused attention on the absence of any obvious successor and the people around him who could try to fill his shoes.

Here are some facts about his most senior allies:

VICE PRESIDENT ELIAS JAUA

Should the president be incapacitated, under the constitution Jaua would in theory take over for the rest of his six-year term, ending in January 2013. He has been the most prominent face of the government during Chavez's absence.

One of Chavez's closest allies for many years, Jaua has been vice president since January 2010 and previously served in his government as agriculture minister and secretary to the presidency.

Born in 1969, the sociologist and former university professor helped found the Socialist Party (PSUV) that swept Chavez into office and was one of the writers of Venezuela's new constitution.

FOREIGN MINISTER NICOLAS MADURO

A former trade unionist, National Assembly president and foreign minister since 2006, Maduro read out the statement that told Venezuelans Chavez had undergone surgery in Cuba.

Maduro, 48, has visited Havana several times during the president's recuperation, according to government sources.

He is married to Cilia Flores, another former president of the National Assembly, and the pair are seen as something of a "power couple" exerting a lot of influence in the government.

Flores, a lawyer who fiercely defends Chavez during her speeches in parliament, was the first woman to serve as head of the Assembly, between 2006-2011, where she now leads the PSUV.

When Chavez was sent to prison following a failed coup attempt in 1992, it was Flores who led the legal team that won him his freedom two years later.

ENERGY MINISTER RAFAEL RAMIREZ

One of the longest-serving senior officials in the administration, Ramirez is also one of the closest to Chavez.

Often seen by outsiders as the de facto number two in the government, he has huge responsibilities running his ministry as well as state oil company PDVSA, one of the biggest in the world. He is often seen on the world stage representing both.

Ramirez, 48, was named energy minister in 2002, just before a prolonged slump in Venezuelan oil production. Then in 2004 Chavez also appointed him to the role of PDVSA president -- two positions never before held by the same person at the same time.

Ramirez was previously a student of Adan Chavez, the president's older brother, at the University of the Andes, where he qualified as an engineering graduate.

GOVERNOR ADAN CHAVEZ

The older brother of the president and also one of his political mentors, Adan Chavez is a physicist by profession who was often counted among the government's "hard-liners."

He was put in charge of strengthening the connections between Venezuela and communist-led Cuba when he was Caracas's ambassador to Havana.

But he left the circle of power around his brother when he decided to pursue the post of governor in their home state Barinas, succeeding their father in the position.

Being so close to the president, many supporters of Chavez have considered him a "safe" choice to succeed him.

But given his more radical left-wing views, he could prove to be a divisive figure and trigger internal disputes within the PSUV -- which he helped to found.

SENIOR PARTY OFFICIAL DIOSDADO CABELLO

During a two-day coup against Chavez in 2002, then-Vice President Cabello briefly assumed the top job.

His first order was to send a group of elite Navy troops to rescue the president, who was being detained by renegade forces at a base on an island in the Caribbean.

The former governor of the country's second most-populous state and a fellow ex-soldier, Cabello joined Chavez in his attempted military coup against former leader Carlos Andres Perez in 1992. Once they were both freed from prison, he became crucial to the campaign that carried Chavez to the presidency.

He has served in various ministerial roles in the government during Chavez's 12 years in power, including infrastructure, the interior, justice, and public works.

Currently he is a member of parliament and senior member of the PSUV.

MARIA GABRIELA CHAVEZ

Often at her father's side, Maria Gabriela carries out some of the official functions of a First Lady. Former Cuban leader Fidel Castro calls her "the heroine", and some observers have gone further, tipping her as a possible successor to Chavez.

The president himself has often said he would like to hand power to a woman. "She was always very close to him (Chavez) and identified with him in so many ways. It is a type of continuation of him," her mother, Chavez's ex-wife Nancy, has said.

(Reporting by Diego Ore, Eyanir Chinea and Marianna Parraga; Editing by Daniel Wallis and Philip Barbara)