Venezuela's leftist leadership on Monday called for a massive show of support for ailing President Hugo Chavez in Caracas on January 10, the day he is supposed to be sworn in to a new six year term.

The request came as the government faced a rising storm of criticism over plans to indefinitely delay Chavez's inauguration if the cancer-stricken leader, still in hospital in Havana, is too sick to be inaugurated.

"All of Venezuela will come here in front of the Miraflores presidential palace, the people supporting our president, the people supporting comandante Chavez -- in an overwhelming manner, the people in the street," said National Assembly speaker Diosdado Cabello.

Cabello, who also heads Chavez' United Socialist Party of Venezuela, said heads of state and government were expected to attend the giant rally as well. Uruguay's President Jose Mujica confirmed that he would be in Caracas.

The Catholic church waded into the controversy, with a veiled warning to the government that it would be "morally unacceptable" to override the constitution and that Chavez's prolonged absence had put the country's stability at risk.

And a key opposition figure on Sunday called for street protests if the government pushes past the January 10 date without Chavez being sworn in.

The Venezuelan president, 58, has not been seen in public since he underwent a fourth round of cancer surgery in Cuba nearly a month ago, his longest absence of his 14 years in power.

Asked whether Chavez's presence in Caracas to take the oath of office Thursday had been ruled out, Cabello said, "We rule out absolutely nothing.

"But we're not going to get to the 10th and not know what we are going to do. We know what we're going to do," he added.

The assembly speaker, considered the regime's third most powerful figure, insisted they were acting within the constitution and accused the opposition of organizing a destabilizing "civic strike."

"With respect to the call for protests and the civic strike, we are saying we are calling the people to the streets on the 10th," he said, adding that there would be no confrontations with the opposition.

"It's a day for the Venezuelan people, for the revolutionary people, to demand respect and recognition once and for all for this constitution of all the Venezuelan people," he said.

Although the government has not directly said Chavez is too sick to be sworn in on January 10, it has begun laying out a legal rationale for him to continue in office while putting off the oath-taking to a later date.

With a pocket-sized constitution in hand, Vice President Nicolas Maduro argued Friday that the charter provides "a dynamic flexibility" that allows the president to take the oath of office before the Supreme Court at some later date.

The position was reaffirmed Sunday by Venezuelan Attorney General Cilia Flores.

Under the constitution, new elections must be held within 30 days if the president dies or is permanently incapacitated either before he takes office or in the first four years of his six-year term.

In that event, the National Assembly speaker is supposed to run the country in the interim. But Cabello has bowed to Maduro's plan to keep the current government in place.

"People should get ready to protest and rebel against what will be a failure to uphold the constitution," said Julio Borges, national coordinator of the opposition Justice First party.

"We are preparing a real campaign, which will involve going to institutions, countries, embassies and organizations outside of the country to let them know that authorities are trying to twist the constitution due to an internal problem."

In a statement, the church said the president's prolonged sickness "puts at grave risk the political and social stability of the nation."

The public is "confused, and a good part of it angry," it said, because not a single medical report on his condition has been released.

"The government has not told the people the whole truth, which it has the full right to receive with certitude; it has only communicated, with evident difficulty, its political truth."

Maduro, taking reporters' questions as he toured an elementary school, said the government needed time to study the document.

But he warned the church "not to fall into the temptations of the past, but on the contrary to support the stability, tranquility and progress of the country." (AFP)