CARACAS (Reuters) - Venezuelan opposition leader Henrique Capriles will challenge the late Hugo Chavez's preferred successor for the presidency of the South American OPEC nation next month, sources said on Sunday, setting the stage for a bitter campaign.
Capriles will face election favorite and acting President Nicolas Maduro. The pair have until Monday to register their candidacies for the April 14 vote.
The election will decide whether Chavez's self-styled socialist and nationalist revolution will live on in the country with the world's largest proven oil reserves.
Capriles, 40, a centrist state governor, will formally announce his decision to run later on Sunday, two sources in his camp said.
"There's a lot of negativity around. It's going to be tough, but we're going to do it," one of the sources told Reuters. "Henrique's made his decision. He's not backing down."
Former vice president Maduro, 50, a hulking one-time bus driver and union leader turned politician who echoes Chavez's anti-imperialist rhetoric, is seen winning the election comfortably, according to two recent polls.
Maduro pushed for a snap election to cash in on a wave of empathy triggered by Chavez's death on Tuesday at age 58 after a two-year battle with cancer. He was sworn in as acting president on Friday to the fury of Capriles.
Capriles, the youthful Miranda state governor who often wears a baseball cap and tennis shoes, lost to Chavez in October. But he won 44 percent of the vote - the strongest showing by the opposition against Chavez.
Capriles has accused the government and Supreme Court of fraud for letting Maduro campaign without stepping down.
Although the ruling Socialist Party is favored to win, opposition supporters are trying to raise their spirits.
"There's no reason to think that the opposition is condemned to defeat," Teodoro Petkoff, an anti-government newspaper editor, said on his Sunday morning talk show.
Maduro has vowed to carry on where Chavez left off and ratify his policy platform. He acknowledged he has big shoes to fill.
"I am not Chavez - speaking strictly in terms of the intelligence, charisma, historical force, leadership capacity and spiritual grandeur of our comandante," he told a crowd on Saturday.
Chavez was immensely popular among Venezuela's poor for funneling vast oil wealth into social programs and handouts.
The heavy government spending, along with currency devaluations, has contributed to annual inflation of more than 20 percent, hurting consumers.
"Maduro's success will depend on if he can fix the economy and its distortions," said a former high-level official in the Chavez government who declined to be named. "If he does that, he could emerge as a strong leader instead of one who is an heir."
Maduro's first official meeting on Saturday was with officials from China, who Chavez courted to provide an alternative to investment that traditionally came from the United States.
He has adopted his mentor's touch for the theatrical, accusing imperialists, often a Chavez euphemism for the United States, of killing the charismatic but divisive leader by infecting him with cancer.
Emotional tributes were paid at a religious service at the military academy housing Chavez's casket on Sunday, where people continued to gather.
Chavez railed against the wealthy and scared investors with nationalizations. In heavily polarized Venezuela some in the well-to-do class toasted his death with champagne.
Venezuela's opposition coalition backed Capriles as its candidate on Saturday. Capriles says, if elected, he would copy Brazil's "modern left" model of economic and social policies.
Given the state resources at Maduro's disposal and the limited time for campaigning, Capriles faces an uphill battle.
"If the opposition runs, they'll lose. If they don't run, they lose even more!" tweeted Andres Izarra, who served as information minister under Chavez.
The opposition rank-and-file is heavily demoralized after losing last year's presidential race and getting hammered in gubernatorial elections in December, stoking internal party divisions.
"There's no doubt that it's an uphill race for Capriles," local political analyst Luis Vicente Leon said. "Maduro is not Chavez. ... (But) the trouble is that given the race is so close to Chavez's death, emotions get inflamed and the candidate probably continues to be Chavez rather than Maduro.
"The big challenge for Capriles is not to campaign against Chavez but to try to take the fight to Maduro ... trying to show the huge gap (with Chavez) and relate it to the daily problems Venezuelans face."
(With reporting by Ana Isabel Martinez, Simon Gardner, Terry Wade, Pablo Garibian, Deisy Buitrago, Mario Naranjo and Enrique Andres Pretel)