Ailing Hugo Chavez to miss inauguration date

NEW: Officials say Hugo Chavez will not be in Venezuela for inauguration day NEW: Government, opposition differ on what happens next; lawmakers debating issue Chavez's term automatically renews, the government says The Constitution makes it clear that this is not the case, opponents say

(CNN) -- Medical treatment in Cuba will keep Venezuelan President Hugo Chavez from being sworn in for a new term this week, a top official said Tuesday.

At the same time, supporters and opponents of Chavez are bracing for a legal battle over whether the inauguration can be postponed.

Venezuela's vice president said in a statement Tuesday that the inauguration would occur before the country's Supreme Court at a "later date," hours after the opposition called on the nation's top court to decide whether that's possible.

Chavez has been undergoing cancer treatment in Cuba for the past month, most recently experiencing respiratory complications.

Venezuela's Constitution provides guidance on what should occur if a president cannot be inaugurated before the National Assembly, but supporters and critics of Chavez have different interpretations.

A statement from Venezuela's vice president read before lawmakers Tuesday said that the constitution authorized "at a later date, the swearing-in before the Supreme Court."

"The process of post-surgical recuperation must continue past January 10 of this year, so he will not be able to appear on that date before the National Assembly," the statement said.

Lawmakers were fiercely debating the issue Tuesday afternoon.

Henrique Capriles, the man Chavez defeated at the polls in October, said earlier Tuesday that the Supreme Court must clarify the confusion.

"There is a conflict here. What is the Supreme Court waiting on?" Capriles asked.

As far as the opposition is concerned, Capriles said, the constitution is clear that the president's term ends on January 10 and a new period begins.

If Chavez is unable to be sworn in, it creates a leadership vacuum that must be filled by the National Assembly president, and the possibility of new elections arise, Capriles said.

National Assembly President Diosdado Cabello has said that he has no intention of assuming power if Chavez is not sworn in.

The government contends that Chavez's new term begins automatically because he was re-elected and that the inauguration could be held later.

"When (the opposition) talks about a power vacuum, they are proposing a coup," Cabello said, the state-run AVN news agency reported.

There is no such automatic continuity of power, Capriles said, arguing that "the only thing that has continuity are the country's problems."

"If the constitution is not followed, or there is a conflict of interpretation, the Supreme Court has to take a position," he said.

Capriles expressed concern about unrest or political crisis in the absence of a decision by the high court.

Chavez, 58, has not been seen in public since arriving in Havana for his fourth cancer operation in early December, fueling speculation that his health is worse than the government is letting on.

Last week, a government spokesman said Chavez was battling a severe lung infection that has caused respiratory failure. Ernesto Villegas said the president was following a strict treatment regimen for "respiratory insufficiency" caused by the infection.

His condition remained unchanged as of Monday, the government said in a statement.

"Treatment has been administered permanently and rigorously, and the patient is supporting it," the statement said.

If Chavez is unable to be inaugurated before lawmakers on Thursday as scheduled, the constitution says he can be sworn in before the Supreme Court.

But the wording is not clear about whether the inauguration before the Supreme Court must occur on Thursday, whether it must occur in the country or who should run Venezuela in the meantime.

Chavez's party has called for his supporters to gather in front of the presidential palace on Thursday in support of the president.