The two men vying to replace the late Venezuelan president, Hugo Chavez, have addressed tens of thousands of people on the first official day of campaigning for this month's election.
The acting president, Nicolas Maduro, began his campaign in Mr Chavez's hometown, Sabaneta de Barinas.
He vowed to continue his programme of social reforms.
Opposition candidate Henrique Capriles said in Monagas state the government would do anything to hold on to power.
He called on his supporters to go to the polls on 14 April.
"All I have is the power of the people. I don't have the support of the courts," he told tens of thousands of his supporters in Maturin, capital of the eastern state of Monagas.
"Each one of you should take the campaign to your homes, to your neighbourhoods," said Mr Capriles, who was defeated by Mr Chavez in last year's presidential election.
The official campaign has just begun, but the two main candidates have already been holding events since Mr Chavez died of cancer on 5 March after 14 years in office.
Mr Maduro explained why he decided to begin the campaign in Mr Chavez's home state of Barinas.
"We are here to make a commitment to the land where he was born: we will not let the people down and we will go to the very end to build socialism."
He reminded voters he had been chosen by the late president to continue his programme of social reforms.
"We can say out loud that our people have never betrayed Hugo Chavez. We never let him down. The people are ready to continue the revolution, the historic legacy he has left us," Mr Maduro said to a crowd of supporters in Sabaneta de Barinas' main square.
After the first events in Barinas state, Mr Maduro will follow the route Mr Chavez travelled during the previous presidential campaign six months ago, hoping that he, too, will end it in the presidential palace.
The BBC's Irene Caselli in Caracas says even though these are the first elections without the presence of Mr Chavez for almost two decades, he continues to dominate the campaign.
Mr Maduro has continually invoked the memory of Mr Chavez and called himself his son and apostle, while Mr Capriles has told his supporters that Mr Maduro is not as competent as the late president.
Mr Capriles has also focused on insecurity in the country, saying that the government has failed to put forward "a single proposal to defeat violence and give peace to Venezuela".
According to interior minister Nestor Reverol, 3,400 murders were recorded in Venezuela in the first three months of 2013.
Polls suggest Mr Maduro has a lead of 14 points over Mr Capriles, with the remaining five candidates for the presidency trailing far behind.