Havana (CNN) -- Venezuelan President Hugo Chavez arrived Monday in Cuba for surgery just days after saying his cancer had returned.
State-run VTV showed Chavez embracing Vice President Nicolas Maduro and other top Venezuelan officials before his plane took off early Monday.
If the president dies, Venezuela's constitution specifies that the vice president assumes the presidency until new elections can be held.
Chavez called for voters to take things a step further.
"My firm opinion, as clear as the full moon -- irrevocable, absolute, total -- is ... that you elect Nicolas Maduro as president," Chavez said, waving a copy of the Venezuelan Constitution as he spoke. "I ask this of you from my heart. He is one of the young leaders with the greatest ability to continue, if I cannot."
It was the first time Chavez had spoken publicly about the possibility of a successor -- a shocking subject from a man who looms larger than life in Venezuela and in Latin American politics.
"This is huge. He could have said something indirectly. He could have said something like, 'We'll have to see. Let's talk about it when the time comes,'" said Javier Corrales, a professor of political science at Amherst College in Massachusetts. "He switched from being very evasive to very articulate. That must have been the result of a major change in health for the worse."
Venezuela's information ministry said Monday that Chavez was optimistic as he headed to Cuba for treatment.
Cuban President Raul Castro met him in Havana, the information ministry said. Ecuadorian President Rafael Correa said in a Twitter post that he was on the way to visit Chavez there.
Chavez, who had surgery in 2011 to remove a cancerous tumor, has undergone further surgery and radiation in Cuba since then. He declared himself cancer-free in July.
Health rumors dogged Chavez on the campaign trail this year, but didn't stop him from winning re-election in October.
The president has repeatedly spoken publicly about his cancer battle, but has never specified the type.
The government has released few specifics, fueling widespread speculation about his health and political future, and sparking criticism from political opponents.
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.
CNN's Catherine E. Shoichet, Patrick Oppmann, Dana Ford and Rafael Fuenmayor contributed to this report.