Ailing President Hugo Chavez cannot return home in time for his inauguration on Thursday and so will take the oath of office at a later date before the Supreme Court, the government announced.
The announcement confirming that Chavez, 58, is too sick to be sworn in on the January 10 inauguration day came in a letter to the National Assembly from Vice President Nicolas Maduro.
"According to the recommendation of the medical team... the process of post-operative recovery must extend beyond January 10 of the current year, and as such he will not be able to appear on that date before the National Assembly," said the letter, read out by National Assembly speaker Diosdado Cabello.
The letter went on to say that, in keeping with article 231 of the constitution, Chavez would take the oath before the Supreme Court at a later date.
The long-expected decision came amid a storm of controversy over whether his current term can be extended beyond January 10, and calls by the opposition for the Supreme Court to intervene.
"I do not know what the judges of the Supreme Court are waiting for. Right now in Venezuela, without any doubt whatsoever, a constitutional conflict has arisen," opposition leader and former presidential candidate Henrique Capriles said.
In the National Assembly, deputies on both sides of the aisle stood up to make angry speeches for and against the government's decision to delay the swearing-in and extend his current term beyond January 10.
Cabello, the assembly speaker, taunted the opposition and said the ruling party had no doubts that the course it was taking was constitutional.
"If anyone has doubts, then go to the Supreme Court, Go ahead to the Supreme Court, explain what your doubts are," he said. "We don't have any doubts about what we have to do, and what is here in the constitution."
He also vowed that Chavistas would take to the streets "defending the constitution, defending the law, defending the people, defending the decision that was made."
The government says the swearing-in is a mere formality that can be delayed, but the opposition says Chavez must at least be declared temporarily incapacitated and replaced on an interim basis by the National Assembly speaker.
Throughout his illness, first detected in June 2011, Chavez has refused to relinquish the powers of the presidency, even when leaving for Cuba for his fourth and most difficult round of surgery.
The charter also says new elections must be held within 30 days if the president-elect or president dies, or is permanently incapacitated, either before he takes office or in the first four years of his six-year term.
"There must be a response from our institutions in the face of this conflict," insisted Capriles, who lost to Chavez in October by an 11-percent margin but gave him the toughest political fight of his 14-year tenure.
Capriles also urged Latin American leaders -- Chavez has long been the figurehead of the anti-US left in the region -- to stay away from a rally convened by the government for Thursday in place of the inauguration.
So far Uruguay's President Jose Mujica, Bolivia's President Evo Morales and Foreign Minister Ricardo Patino of Ecuador are the only ones to confirm their attendance.
"Chavez's health is no longer in our hands," said Mujica in an interview with the Montevideo newspaper La Republica. "Our function is to back the government and people of Venezuela."
Capriles urged regional leaders not to succumb to "a game by a political party" -- alluding to Venezuela's ruling party. He mentioned by name the presidents of Argentina, Brazil, Colombia and Bolivia and Ecuador.
Earlier, the country's main opposition coalition turned to international organizations for support.
It warned the Organization of American States of an "alteration of the constitutional order" if the government retains its grip on power regardless of Chavez being unable to take the oath of office.
In Washington, the State Department said Venezuelans should decide for themselves what to do without resorting to violence, calling for a "broad based discussion."
"And it needs to be decided in a manner that is free, fair, transparent, is seen as ensuring a level playing field in Venezuela," said State Department spokeswoman Victoria Nuland.
Information Minister Ernesto Villegas said late Monday that Chavez's medical condition had been unchanged since the latest complication from surgery was reported four days ago.
Chavez is suffering from a severe pulmonary infection that has resulted in a "respiratory insufficiency," officials have said.