The president has repeatedly spoken publicly about his cancer battle, but has never specified what type he has.
The government has released few specifics, fueling widespread speculation about his health and political future, and sparking criticism from political opponents.
"This has not been handled with the transparency and the truth that our people deserve," opposition Rep. Julio Borges said Sunday.
But Diosdado Cabello, a close Chavez ally and the president of the National Assembly, countered that claim.
"By God, since the first day he has spoken clearly. These men are trying to have a party with the president's illness," he said. "It's going to turn out well. He continues being the head of state and the head of the government. He continues being the president of the republic, under any circumstance."
State-run VTV Sunday showed throngs of supporters cheering and praying in support of Chavez.
An opposition coalition leader told CNN affiliate Globovision that the opposition would be prepared for a new presidential vote.