Opposition leader Henrique Capriles has launched his bid to succeed Hugo Chavez in Venezuela.
After confirming he will run in the April 14 elections to replace Mr Chavez, who died last week, he made a no-holds-barred attack on the government, accusing it of betraying Venezuelans' trust.
Many consider his campaign doomed, as Mr Chavez defeated him by a 12-point margin in October.
During Sunday night's announcement, he accused opponent Nicolas Maduro of using Mr Chavez's corpse as a campaign prop. Mr Maduro is Mr Chavez's hand-picked successor.
Mr Capriles, 40, said Mr Chavez's political heirs have toyed with Venezuelans' hopes, lying to them about his deteriorating health by suggesting he could recover and even producing decrees he supposedly signed.
He did not make direct reference to the decision to embalm Mr Chavez and put him on permanent display, but he said: "You are playing politics with the president's body."
He accused the socialist government that Mr Chavez led for 14 years of meticulously planning a campaign to assure the election of Mr Maduro. "Who knows when President Chavez (really) died," he said. The government says Mr Chavez succumbed to cancer on Tuesday after a nearly two-year battle. It has offered almost no clinical information.
Mr Capriles also called Defence Minister Diego Molero a "disgrace" for publicly backing Mr Maduro. The constitution forbids the military from taking political sides.
"Don't fool yourselves that you're the good and we're the bad," Mr Capriles said in a 45-minute speech at his Caracas campaign headquarters. "No, you're no better than us. I don't play with death. I don't play with pain."
With a picture of Mr Chavez behind him, Mr Maduro appeared almost immediately on state TV, accusing "the losing, miserable candidate" of defaming Mr Chavez and his family. He called Mr Capriles a "fascist" trying to provoke violence by insulting the "crystalline, pure image of Commander Chavez". Mr Maduro said: "You have made the biggest mistake of your life."