Venezuela\'s united opposition voted Sunday in a first-ever primary which was expected to see youthful state governor Henrique Capriles chosen to challenge President Hugo Chavez in an October election. Balloting began throughout the country at 1230 GMT and is scheduled to end at 2030 GMT, as Venezuelans headed to 7,600 polling stations nationwide. Five candidates are running in the opposition contest led by Capriles, 39, the energetic governor of Miranda state and frontrunner, according to surveys. The 57-year-old Chavez, who last year underwent chemotherapy in Caracas and Havana and now claims to be cancer-free, is seeking a third six-year term in the October 7 vote. Capriles, telegenic and energetic, has been in politics since he was 25. His campaign got a boost last month when Leopoldo Lopez, a popular former mayor, dropped out and endorsed him. He describes his politics as center-left, and has argued that Venezuela can \"replicate\" Brazil\'s model of economic development: allowing markets to play their role while also making social progress a priority. Capriles is also known for having confronted Chavez, a fiery critic of the United States, back in 1999 when the governor was a lawmaker. The opposition favorite\'s main rival in the ballot is Pablo Perez, 42, of the Un Nuevo Tiempo (A New Era) party. Perez governs Zulia, Venezuela\'s most populous and wealthiest state. Both Perez and Capriles say they want to end the country\'s deep political polarization and have pledged to fight poverty. They have campaigned with a conciliatory message and have avoided directly criticizing Chavez, the main political and economic ally of Cuba, the only one-party communist regime in the Americas. They also propose continuing and improving the popular social programs adopted by the Chavez government since 2003, notably in health and housing. The other candidates in the race are independent legislator Maria Corina Machado, labor leader Pablo Medina, and former ambassador Diego Arria. Unlike the governors, all three have chosen to aggressively challenge Chavez. \"This (vote) is not about changing the president. It is about changing a model that has failed,\" Capriles said on the campaign trail last week. A lawyer with movie-star looks whose family includes Jewish immigrants, Capriles would seem to embody a generational change as well as a political one. Capriles and Perez have emerged in recent months \"as favorites precisely because they sought to depolarize the country and refrained from confronting Chavez,\" said historian Margarita Lopez Maya. Ballots were also being cast Sunday in Venezuela\'s sizeable expatriate community in Florida, where 20 polling stations opened to accommodate voters. There are an estimated 18,000 Venezuelans in this part of the United States, many of whom are eager to see change in their homeland. \"This is a process that reaffirms our commitment to democracy,\" said Pedro Mena, leader of a prominent opposition group in Miami. \"Venezuelans who live here, we know that we can make a difference in the outcome of the presidential election,\" he said. In January the opposition parties unveiled a unity platform focusing on free-market economics and emphasizing public safety. The document calls for an end to price controls, in place since 2003; adoption of a competitive currency exchange rate; reassessing Chavez\'s creation of a socialist state; and returning autonomy to the Central Bank.