Venezuelans have lined up to vote in the country's first-ever opposition presidential primary, choosing a single challenger to take on President Hugo Chavez after 13 years in office.
Henrique Capriles, the front-runner among five contenders according to pre-election polls, predicted a high turnout.
"We're going to surpass all expectations of participation," said Mr Capriles after voting in Caracas. "Today is a day for Venezuelans' future."
Opposition supporters seemed less interested in the proposals put forth by the contenders than their chances of defeating Mr Chavez in the October presidential election.
The outcome will set the stage for what many are billing as the most anticipated presidential contest since Mr Chavez's first triumph in 1998, and Venezuelans on both sides of the nation's political divide are eager to see who will emerge as the challenger.
"I think this time there will be a change," said Edgar Arvais, a 57-year-old engineer who emerged from a polling station at a school after casting his ballot for Zulia state governor Pablo Perez. He said crime and a weak economy are top concerns, and the opposition this time is "very strong, very determined".
Carmen Gloria Padilla, a 66-year-old telephone company employee, said she was voting for Mr Capriles, who is the governor of Miranda state and has attracted a large following as a charismatic, youthful alternative.
"He's going to be the candidate who can get us out of this giant hole we're stuck in," she said.
Mr Chavez, however, proved himself a tireless campaigner as he easily sailed to election victories in 1998, 2000 and 2006. He spent the day at the "Day of Revolutionary Youth" parade in Aragua state, wearing the presidential sash and applauding as supporters marched past in formation.
During his marathon televised addresses, Chavez declared it does not matter who emerges as the opposition's candidate because he is confident none of his rivals are capable of beating him. He repeatedly taunted would-be challengers, portraying them as agents of Venezuela's wealthy elite and Washington.