Venezuelan opposition leader Henrique Capriles has announced that he will run in next month's presidential election to replace the late Hugo Chavez.
He faces an uphill battle against acting President Nicolas Maduro, who was sworn in last week and was Chavez's hand-picked successor.
According to state news, the candidates have until Monday to register for the April 14 election.
"Nicolas, I will not give you a free path," Capriles told reporters Sunday. "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.
He 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.
Maduro quickly fired back, appearing on state-run VTV to counter Capriles, calling him irresponsible.
"His aim is to provoke the Venezuelan people," Maduro said. "He's looking for violence."
The sharp exchange gave a potential preview of what the campaign period might look like -- angry, bitter and deeply divided.
Earlier Sunday, Maduro, 50, the ruling Socialist Party's candidate, picked up an endorsement from the country's small Communist Party.
He vowed to continue the policies and vision of Chavez, who died last week of cancer.
Chavez was a larger-than-life leader, who positioned himself as a champion of the poor and cast himself as a "21st-century socialist."
He was a polarizing figure, revered by legions even as others accused him of repressing dissenting voices and turning over once-independent institutions to partisan loyalists.
"I will be president and commander in chief of the armed forces because that's what Chavez ordered me to do. I will follow his orders, but I need the help of the people," Maduro said, according to VTV.
When Maduro was sworn in last week, Capriles protested loudly, telling reporters in Caracas the ceremony was "an abuse of power."
"To be president, the people have to elect you," he said. "The constitution is very clear."
Maduro addressed the upcoming election.
"May the best person win," he said. "The people will decide."