CARACAS, Venezuela -- Venezuelan lawmakers will meet Saturday in a session that could shed light on what steps may be taken if President Hugo Chavez is too sick to be sworn in for a new term next week.

Legislators will choose a president, two vice-presidents and other leaders of the National Assembly, which is controlled by a pro-Chavez majority. Whoever is elected National Assembly president could end up being the interim president of Venezuela if Chavez is unable to be inaugurated on Thursday as scheduled.

Brewing disagreements over how to handle a possible transition of power also could be aired at the session, coming just five days before the scheduled inauguration day specified in the constitution. Chavez's health crisis has raised contentious questions ahead of the swearing-in, including whether the inauguration could legally be postponed.

The government revealed this week that Chavez is fighting a severe lung infection and receiving treatment for "respiratory deficiency" more than three weeks after undergoing cancer surgery in Cuba. The announcement suggests a deepening crisis for the 58-year-old president and has fed speculation that he likely is not well enough to travel to Caracas for the inauguration.

National Assembly President Diosdado Cabello called on Chavez backers to show up for the legislative session and demonstrate their support.

"This National Assembly is revolutionary and socialist. It will remain beside the people and our commander," Cabello said in one of several messages on his Twitter account. "If the opposition thinks it will find a space in the National Assembly to conspire against the people, it's mistaken once again. It will be defeated."

Opposition leaders have demanded that the government provide more specific information about Chavez's condition, and say a new election should be held within 30 days if the president doesn't return to Venezuela by inauguration day.

Some Chavez allies say the inauguration date is not a hard deadline, and argue that the president should be given more time to recover from his surgery if necessary.

Chavez hasn't spoken publicly or been seen since his Dec. 11 operation in Cuba. In a Thursday night update, the government for the first time described the president's respiratory infection as "severe," the strongest confirmation yet that Chavez is having serious trouble breathing after days of rumours about his condition worsening.

"Chavez has faced complications as a result of a severe respiratory infection. This infection has led to respiratory deficiency that requires Commander Chavez to remain in strict compliance with his medical treatment," Information Minister Ernesto Villegas said Thursday night, reading a statement on television.

The government's characterization raised the possibility that Chavez might be breathing with the assistance of a machine. But the government did not address that question and didn't give details of the president's treatment.

Independent medical experts consulted by The Associated Press said the government's account indicated a potentially dangerous turn in Chavez's condition, but said it's unclear whether he is attached to a ventilator.

"It appears he has a very severe pneumonia that he suffered after a respiratory failure. It is not very specific," said Dr. Alejandro Rios-Ramirez, a pulmonary specialist in Puerto Vallarta, Mexico.

Dr. Gustavo Medrano, a lung specialist at the Centro Medico hospital in Caracas, said he has seen similar cases in cancer patients who have undergone surgery, and "in general it's very bad, above all after a surgery like the one they performed on him."

"I don't know the magnitude of the infection he has, how much of his lungs have been compromised, how much other organs are being affected. That's not clear," Medrano said.

"What's most likely is that he's on mechanical ventilation," Medrano added. However, he said, while respiratory deficiency means there is an abnormally low concentration of oxygen in the blood, depending on the severity it can be treated in various ways.

Dr. Michael Pishvaian, an oncologist at Georgetown University's Lombardi Cancer Center in Washington, agreed that such respiratory infections can run the gamut from "a mild infection requiring antibiotics and supplemental oxygen to life-threatening respiratory complications."

"It could be a very ominous sign," Pishvaian said. He said it's possible Chavez could be on "life support," but added it's impossible to be sure without more details.

The government expressed confidence in Chavez's medical team and condemned what it called a "campaign of psychological warfare" in the international media regarding the president's condition. Officials have urged Venezuelans not to heed rumours about Chavez's condition.

Opposition leaders have blamed vague information coming from the government for the rumours, and demanded a full medical report.

The Venezuelan newspaper El Nacional criticized what it called an "information vacuum" in an editorial on Friday, saying Venezuelans are in the dark because "no one speaks clearly from the government." The newspaper called the situation reminiscent of secrecy that surrounded the deaths of Josef Stalin in the former Soviet Union and Mao Zedong in China.

State television repeatedly played video of a song in which rappers encourage Venezuelans to pray, saying of Chavez: "You will live and triumph." A recording of a speech by Chavez appears during the song, saying: "I will be with you always!"

Chavez has undergone four cancer-related surgeries since June 2011 for an undisclosed type of pelvic cancer. He also has undergone chemotherapy and radiation treatment.

He was re-elected in October to another six-year term, and two months later announced that the cancer had returned. Chavez said before the operation that if his illness prevented him from remaining president, Vice-President Nicolas Maduro should be his party's candidate to replace him in a new election.

This week, Cabello and the president's elder brother Adan joined a parade of visitors who saw Chavez in Havana, and then returned to Caracas on Thursday along with Maduro.

Brazil's state-run Agencia Brasil news agency reported Friday that President Dilma Rousseff's top international adviser, Marco Aurelio Garcia, made a one-day visit to Cuba and spoke with Venezuelan and Cuban officials about Chavez's health. It was unclear if Garcia actually saw Chavez, or what day he visited Cuba.

Telephone calls placed after hours to Brazil's Foreign Ministry and presidential offices were not immediately answered.

The Venezuelan Constitution says the presidential oath should be taken Jan. 10 before the National Assembly. Government officials have raised the possibility that Chavez might not be well enough to do that, without saying what will happen if he can't. The constitution also says that if the president is unable to be sworn in before the National Assembly, he may take the oath office before the Supreme Court.

The constitution says that if a president or president-elect dies or is declared unable to continue in office, presidential powers should be held temporarily by the president of the National Assembly and a new election should be held within 30 days.

On the streets of Caracas, some of Chavez's supporters say they're still holding out hope he can recover.

"He's the only leader of the revolution," said Miriam Bolivar, who belongs to a grassroots pro-Chavez group. "We can't imagine life without him. He's our life. This is one more battle and we have faith that he'll come out it unscathed once again."

Other Chavez supporters say they're unsure what to believe about his condition and express misgivings about the president's lieutenants.

"We hope that what they're telling us is true," said Ricardo Maya, a supporter who was reading a newspaper in a city square. "Chavez has all my confidence. He always speaks the truth. I can't say the same about the people around him."