Women shriek and whip out their camera phones as political activists begin chanting "Sí, se puede!," the Spanish-language version of "Yes, we can!"

Several dozen residents of a nearby hillside barrio have gathered in a small plaza to meet a new crop of local candidates, but the wave of gasps that rolls over the crowd as former Mayor Leopoldo Lopez arrives reveals who is the star of the show.

"I'm here to back him, to support him and his candidacy for president," says Isabel Lozada, a secretary from a modest Caracas district. "He's a young man with good ideas." Her friend, Rosario Contreras, adds, "He's a fighter, especially for humble people like us, the people from the barrio."

As more voters like Ms. Contreras voice their disillusionment with President Hugo Chávez's leftist government, Mr. Lopez and other opposition candidates are crisscrossing the nation, organizing rallies and hoping to build on what they say is a growing chorus for political change.

Sensing that this could be their best shot at victory, all the parties opposed to Mr. Chávez have agreed to put aside their differences and back a single candidate to be chosen in a February primary. The Harvard-educated Lopez, who long advocated for such a primary, hopes to be among the candidates but says he will support whichever nominee is picked.

"This candidate will have to be assumed as the captain of the team, but one who cannot win without the rest of the team," says Lopez.

The decision to hold a primary is a victory for a younger generation of Venezuelan leaders who for some years were locked in a generational battle with traditional party elders, most of whom held seats before Chávez stormed onto the political scene in the late 1990s. The new leaders are, on average, around 40 years old and have embraced Chávez's populist vision but believe that private investment and economic growth are the best ways to fight poverty.

"They represent the future, the faces of change, and likely have a better probability of winning against [Chávez]," says Alejandro Grisanti, chief economist at Barclays Capital. "It will be harder for Chávez to say one of these young candidates represents the past."

Unlike previous opponents to Chávez, who in the early years of his administration refused to take part in elections, saying the electoral process was rigged, these new leaders are seeking votes in the president's traditional turf.

"It's not enough to be a majority. We have to be an organized majority," Lopez told the small group assembled on a recent night. "Being an organized majority means having a presence in every barrio, in every subdivision, in every small town spreading our message of change. This means leaders who go house to house."

While he is one of the opposition's most telegenic figures, Lopez was barred from running for office in 2008 by anticorruption officials loyal to Chávez because of charges stemming from an unresolved corruption case.

Lopez and many others say the case was politically motivated to neutralize a potential opponent to Chávez. Lopez is fighting the case in the Inter-American Court of Human Rights and expects a verdict by September. If he wins, he will officially throw his hat in the presidential ring.

Other potential candidates include Henrique Capriles, the governor of Venezuela's second-largest state, and Caracas Mayor Antonio Ledezma, who waged a hunger strike to protest Chávez's moves to strip city and state officials of their authority.

Mr. Capriles has emerged in some polls as Venezuela's most popular politician, polling ahead of even Chávez, whose popularity has been steadily undercut by persistently high crime, double-digit inflation, shortages, and recurring power outages.

"[Chávez] has in his hands all the tools to make this country function, and if he did so everyone would support him," says Josefina Arias, a vendor who describes herself as a former Chávez supporter. "Unfortunately, I believe that Chávez has lost his vision of what Venezuela could be."

Ms. Arias was in the provincial capital of Los Teques with hundreds of others to receive state-funded vouchers from Capriles worth about $3,000 to repair rain-damaged homes.

Capriles says his nonideological focus on fixing everyday problems has helped him gain votes in traditional Chávez strongholds. "I'm first in the polls because I want what the people want: a new leadership based on unity, a government that is equally for everyone," says Capriles.

Both Lopez and Capriles point to last September's legislative elections in which opposition candidates received more votes than Chávez's United Socialist Party of Venezuela as proof that the electoral tide is turning in their favor.

Despite the opposition's popular win, Chávez assigned more electoral weight to sparsely populated regions, assuring his party's dominance in the National Assembly.

"Chávez has won through elections, but his daily maneuvering isn't democratic," Capriles says. "The challenge is to democratically overcome a government that isn't democratic."

Many observers wonder whether the unity will hold, but both Capriles and Lopez say they are certain the primary results will be respected by the other opposition hopefuls, saying it would be "political suicide" to run against whoever wins the primary.

The real challenge, says Lopez, will be maintaining an equilibrium between honest competition among very different options and maintaining a fragile unity that everyone recognizes is the key to winning. The potential for victory is too great to ignore, he believes, and will keep everyone focused and committed.

"The day after the primaries, we will have 335 candidates for mayor, 24 for governor, and one for president hitting the streets of the nation as a monolithic bloc," says Lopez, "which will undoubtedly uphold the political and emotional unity of all Venezuelans."