Backers wearing T-shirts with the slogan "I am Chavez" waved flags while upbeat music from Chavez's last presidential campaign blared from speakers, proclaiming: "Chavez, heart of the people!"
The government organized the unusual show of support for the cancer-stricken leader on the streets outside Miraflores Palace on what was supposed to be his inauguration day. A swearing-in ceremony has been indefinitely postponed, despite opposition complaints.
"We came to show support, so he knows his nation is with him," said Anny Marquez, a secretary and voluntary member of a civilian militia that Chavez has built in recent years. "We're with him in the good times as well as the bad."
The government invited leaders from across Latin America and the Caribbean to add political weight to the inauguration without an inauguree, while the domestic opposition demanded details about Chavez's state and called the delay of the formal swearing-in a violation of the constitution.
Presidents attending from allied countries included President Jose Mujica of Uruguay, Evo Morales of Bolivia and Daniel Ortega of Nicaragua.
Maduro said heads of state, foreign ministers and other officials from 19 countries had come to Caracas and were discussing the Chavez-launched Petrocaribe program, through which the OPEC nation provides fuel under preferential terms to allies.
Vice President Nicolas Maduro, whom Chavez designated his chosen successor last month, said that even though it isn't an official swearing-in, Thursday's event still marks the start of a new term for the president following his re-election in October.
"A historic period of this second decade of the 21st century is starting, with our commander leading," Maduro said.
But glaring above all in the planned event was Chavez's absence from the balcony of the presidential palace where he has so often spoken for hours on television, chided his opponents and called for a socialist revolution.
Some of Chavez's supporters outside the presidential palace wore T-shirts with an image of the president's eyes. His face was everywhere on signs in the crowd, and nearly everyone wore red, the color of his Bolivarian Revolution movement. New murals with Chavez's smiling face have gone up on city walls.