Venezuela’s vice president called in the nation’s top leaders Tuesday hours after ailing President Hugo Chavez apparently took a turn for the worse, and announced on national television that a U.S. embassy attaché was being expelled for meeting with military officers and planning to destabilize the country.

Foreign Minister Elias Jaua also announced the expulsion of a second U.S. official, also a U.S. Air Force attaché.

Supporters of the 58-year-old president visited churches to pray for his health, a day after the government described his condition as “very delicate” after undergoing cancer surgery in December.

Vice President Nicolas Maduro told Venezuela’s high military command and civilian leaders that the U.S. embassy’s air force attaché, Col. David Delmonaco, had 24 hours to leave the country. He said the official had been spying on Venezuela’s military.

U.S. Embassy spokesman Greg Adams confirmed Delmonaco’s identity but had no immediate comment.

In Washington, Army Lt. Col. Todd Breasseale, a Pentagon spokesman, said, “We are aware of the allegations made by Venezuelan Vice President Maduro over state-run television in Caracas, and can confirm that our air attaché … is en route back to the United States.”

'Severe infection'

Late Monday, Communications Minister Ernesto Villegas said Chavez was suffering from “a new, severe infection.” The state news agency identified it as a respiratory infection.

Chavez has been undergoing “chemotherapy of strong impact,” Villegas added without providing further details.

Chavez has neither been seen nor heard from, except for photos released in mid-February, since submitting to a fourth round of surgery in Cuba on Dec. 11 for an unspecified cancer in the pelvic area. It was first diagnosed in June 2011.

The government said Chavez returned home on Feb. 18 and has been confined to Caracas’ military hospital ever since.

Villegas said Chavez was “standing by Christ and life, conscious of the difficulties he faces.”

Country on 'war footing'

Villegas also took the opportunity to lash out at "the corrupt Venezuelan right" for what he called a psychological war seeking "scenarios of violence as a pretext for foreign intervention."

He called on Chavez's supporters, who include thousands of well-armed militiamen, to be "on a war footing."

Upon Chavez’s death, the opposition would contest the government’s candidate in a snap election that it argues should have been called after Chavez was unable to be sworn in on Jan. 10 as the constitution stipulates.

Indeed, the campaigning has already begun, although undeclared. Maduro, who Chavez has said should succeed him, has frequently commandeered all broadcast channels, Chavez-style, to tout the “revolution” and vilify the opposition.

At a small new chapel on the military hospital’s grounds christened “New Hope,” a few dozen supporters gathered to pray for Chavez, many weeping. But the grounds were otherwise eerily quiet, and Caracas’ streets teemed with the usual snarls of traffic, street vendors and bank lines as people went about normal business.

A supporter of Venezuela's President Hugo Chavez holds up a portrait of him while attending a rally in Caracas February 27, 2013. Chavez has run Venezuela for more than 14 years. (Jorge Silva/Reuters)

Chavez has run Venezuela for more than 14 years as a virtual one-man show, gradually placing all state institutions under his personal control. But the former army paratroop commander, who rose to fame by launching a failed 1992 coup, never groomed a successor with his same kind of force of personality.

Chavez was last re-elected on Oct. 7, and his challenger, youthful Miranda state Gov. Henrique Capriles, is expected to again be the opposition’s candidate in any new election.

One of Chavez’s three daughters, Maria Gabriela, expressed thanks to well-wishers via her Twitter account. “We will prevail!” she wrote, echoing a favorite phrase of her father. “With God always.”

Top officials assemble

Vice President Nicolas Maduro is meeting with other top Venezuelan government ministers, the military high command and all 20 loyalist governors in Caracas following word of President Hugo Chavez's deteriorating health.

Among the governors present is Chavez's older brother, Adan.

Maduro is saying on state television that a scientific commission will investigate the possibility Chavez's illness was caused by an enemy attack.

There has been speculation that Chavez's cancer has spread to his lungs and can't be halted.

An oncologist not involved in Chavez's treatment, which has been conducted in tightly enforced secrecy, told the Associated Press that he viewed Villegas' statement as recognition that Chavez's condition is "truly precarious."

The government announced Monday night that Chavez was in "very delicate" condition after suffering a new, severe respiratory infection. Chavez anointed Maduro as his preferred successor before flying to Cuba in early December to undergo a fourth round of surgery for an unspecified cancer in his pelvic area.

The constitution calls for snap presidential elections if Chavez is declared incapable of governing, or dies.