Nicolas Maduro speaks during a meeting with members of his cabinet in Caracas.
Venezuela's vice president flew to Cuba on Friday to visit the ailing Hugo Chavez and his family, while the leaders of Argentina and Peru also traveled to Havana saying they hoped to ask about the Venezuelan president's condition.
The 58-year-old president is fighting a severe respiratory infection a month after he underwent cancer surgery in Havana, his government says.
"I'm leaving for Havana to continue that work of visiting the family, meeting with his medical team, visiting our commander president," Vice President Nicolas Maduro said on television in Caracas.
Cuba's nightly TV news show reported that Maduro had arrived, but did not say whether he made any comments. The Venezuelan was met at the airport by Cuban Foreign Minister Bruno Rodriguez, the show said.
Chavez hasn't spoken publicly or been seen since before his Dec. 11 operation, his fourth cancer-related surgery since June 2011 for an undisclosed type of pelvic cancer.
The government revealed this week that Chavez is receiving treatment for "respiratory deficiency." Medical experts say that might mean he is breathing with the help of a ventilator.
Maduro was making his second trip to Cuba since Chavez's surgery. He said he would meet with Argentine President Cristina Fernandez, who also was visiting Havana, and hoped to meet with Peruvian President Ollanta Humala, who arrived Friday in the Cuban capital.
Fernandez arrived at the Hotel Nacional along Havana's waterfront on Friday morning. Authorities have characterized the Argentine leader's trip as a private visit and her foreign minister said Thursday that she intended to meet with Chavez.
She told The Associated Press in Friday afternoon that she would lunch with Cuban President Raul Castro and his retired brother Fidel. "And then surely I will meet with the family of my companion and dear friend Hugo Chavez," Fernandez said.
Arriving at the Havana airport, Humala did not say if had confirmed plans to meet with Chavez.
"Obviously I will ask, I will see, how is President Chavez's situation," Humala told reporters, saying he wishes Chavez a "quick recovery."
Presidents Rafael Correa of Ecuador and Evo Morales of Bolivia have also visited Havana during Chavez's current stay there.
Peruvian analyst Nelson Manrique said Humala's trip was a reflection of the president's personal friendship with Chavez, as well as political.
"There is a sector that would like Peru to be unconditionally aligned with the United States, but this is more prudent politically to develop a multilateral policy," Manrique said. "It doesn't seem probable that Hugo Chavez will continue governing, but in any of the scenarios 'Chavismo' will be a very strong force in Venezuela.
"It's convenient for the Peruvian government to maintain a relationship, leave the door open, and balance the geopolitical relationship with Venezuela as well," the analyst added.
Maduro was designated by Chavez last month as his chosen successor. Maduro said that while he is in Cuba, Electricity Minister Hector Navarro will remain in charge of affairs as acting vice president. The vice president didn't say when he would return.
Maduro's announcement came a day after the government gathered foreign allies and tens of thousands of exuberant supporters to celebrate the start of a new term for Chavez on Thursday, even as he was too ill to return home for a real inauguration.
Despite opposition claims that the constitution demands a Jan. 10 inauguration, the pro-Chavez congress approved delaying the inauguration and the Supreme Court on Wednesday endorsed the postponement, saying the president could be sworn in before the court at a later date.
Jailed former defense minister Raul Baduel urged his countrymen, especially the military, to resist what he called a "new constitutional coup" by Chavez's allies. The former military chief, who is in prison after being convicted of embezzlement and abuse of power, made the remarks in a vaguely worded letter that was released Friday.
Baduel has insisted he is innocent and dismissed the case against him as a politically motivated reprisal for his opposition to Chavez.
Though he didn't give details about what action he hoped the military would take, Baduel appeared to echo the argument by opposition politicians that Maduro and other Chavez allies are violating the constitution by remaining in office beyond the formal swearing-in date.
The Supreme Court has dismissed that argument, saying the date in the constitution isn't binding if an inauguration is performed before the court rather than the congress, where presidents usually take the oath of office.
Baduel also urged the governments of other countries "not to validate the constitutional coup d'etat that has been set in motion."
A high-ranking military chief, Maj. Gen. Wilmer Barrientos, said the military will respect and obey the Supreme Court's decision. He told the station Union Radio that those who question the court's decision should make their case through legal channels.
National Assembly President Diosdado Cabello, a former military officer who is thought to have close ties to the armed forces, warned in a message on Twitter that Chavez's supporters should be "on alert for actions of violence" similar to bloodshed that preceded a failed 2002 coup against Chavez.
Chavez was briefly ousted in that coup, then was restored to power within two days with the help of military loyalists amid large protests in the streets by his supporters.