(CNN) -- Hugo Chavez's voice boomed through the speakers at a Venezuelan campaign rally Monday, just minutes after the country's interim leader filed papers to run for president.
The message was clear as Nicolas Maduro and his supporters from the United Socialist Party of Venezuela sang along with a recording of Chavez belting out Venezuela's national anthem.
As Maduro spoke to a cheering crowd, a large photo of Chavez saluting hung behind him. As he filed his campaign platform with election officials, the 50-year-old former bus driver and union leader stressed his commitment to continuing the late president's legacy.
"I am not Chavez, but I am his son," Maduro said. "And all together, the people, we are Chavez."
In a national television broadcast less than a week ago, a tearful Maduro, then vice president, announced Chavez's death after suffering from cancer for a long time. Maduro was sworn in as interim president on Friday, and elections are scheduled for April 14.
In December, Chavez didn't mince words when he told Venezuelans who he wanted to succeed him.
"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."
But on Sunday, opposition candidate Henrique Capriles Radonski said he was ready for a tough fight.
"Nicolas, I will not give you a free path," Capriles said to reporters. "You will have to defeat me with votes."
Capriles, 40, ran against Chavez last year and lost. But he mounted one of the fiercest challenges during the late president's 14 years in power. On Monday, he also filed paperwork to run for the presidency, CNN affiliate Globovision reported.
On Sunday, Capriles accused the government of manipulating Chavez's death for political gain.
"My fight is not to be president. My fight is for Venezuela to move forward," Capriles said Sunday night.
Whether Chavez's popular political movement will have enough momentum to win at the polls after his death remains to be seen, analysts have said.
"Since he does not have charisma, he does not have the experience, he does not have military roots, I think that the Cubans and other friends of Chavez are looking at this election with a bit of nervousness," said Lino Gutierrez, a former U.S. ambassador in Argentina and Nicaragua who now runs an international consulting firm.
But it remains probable that with Chavez's party backing him, Maduro has the necessary strength and support to win an election, said Carlos Manuel Indacochea, a professor at George Washington University.
"No victory is absolutely predictable, but it is very likely," Indacochea told CNN en Español on Monday. "It is very likely because again the government will use all the resources of the state and the recent fact of the death and the aura of the leader who has just departed. So it is very likely that he wins the election."
CNN's Dana Ford and Juan Carlos Lopez contributed to this report.