Every happy democracy is happy in its own way. Unhappy dictatorships are all alike: They don't hold fair elections. With apologies to Leo Tolstoy—who was writing about families—that's a good way of thinking about what Venezuelan democrats are up against as they again set about to remove Hugo Chávez by means of the ballot box.

A primary election in Venezuela next Sunday will be the first step in the latest effort as Chávez opponents try to organize a common front for the Oct. 7 presidential election. Despite a record of chavista election chicanery, the loyal opposition insists that Mr. Chávez can be beaten if the anti-Chávez vote unites behind a single candidate.

To that end, five opposition candidates belonging to the Coalition for Democratic Unity (known in Spanish by the unfortunate acronym MUD) will face off in the primary. All candidates have agreed to back the winner.

MUD will also mobilize an army of poll watchers in the general election to minimize tampering. Yet a bigger problem may be the fact that many Venezuelans believe that their ballots, cast electronically, are not secret. With an estimated five million people employed by the government, it is easy to see how Big Brother intimidation can alter the outcome of an election. Don't forget too that Mr. Chávez has the power of the federal purse on his side and he is already using it. Government spending is booming and there are countless promises of subsidies to come if Mr. Chávez is re-elected.

Because of the loaded dice, the opposition sat out the election for congress in 2005 as a protest, and that inadvertently gave Mr. Chávez 100% control of the congress. The lesson that his opponents learned is that they at least have to try. Achieving a healthy turnout of two million voters will be crucial to establishing the candidate's credibility.

If voter surveys are correct, the MUD candidate is likely to be 39-year-old Henrique Capriles Radonski, governor of the state of Miranda. In December, Mr. Capriles was already polling at an estimated 50% among those who intend to vote in the primary. Since then a popular former mayor of a Caracas municipality withdrew from the race and threw his support behind Mr. Capriles, boosting the governor's chances further.

Mr. Capriles has been a national political figure for more than a decade, and he is the youngest person ever to be speaker of the lower house. He was an early opponent of Mr. Chávez, and in 2004 the president jailed him, claiming that he had incited violence outside the Cuban Embassy in Caracas in 2002. He was eventually cleared of all charges.

His 2008 defeat of Diosdado Cabello—who many believe is Mr. Chávez's anointed successor should the president go to meet his maker—in the Miranda gubernatorial election has convinced some Venezuelans he can beat the incumbent.

Yet for those who would like to see Venezuela renounce socialism, Mr. Capriles is not the best man for the job. That man is a woman, Maria Corina Machado, who won her congressional seat in the last election with the greatest number of votes of any candidate in the country.

Whereas Mr. Capriles emphasizes education as the way in which he will end the marginalization of millions of Venezuelans, Ms. Machado talks the language of markets and liberty. She speaks of "Peoples' Capitalism" and of ending Venezuelan dependence on the state. She is the only candidate who has called for private investment in the oil sector.

Some say the Machado platform is too radical for an impoverished population that has been marinated for decades in the idea that they are rich because of the oil revenues and that the only challenge is just distribution. Perhaps. But a more serious problem is the avarice of the political machine, greased by oil income and heavily reliant on voter dependency on the state.

In other words, Ms. Machado would break too many rice bowls among those living off government contracts. If you know Washington, you know what I mean. Plus she doesn't have a party and lacks the organization that Mr. Capriles has developed after more than a decade in politics. It is no surprise that she's a long shot.

The more populist Mr. Capriles may be the best any anti-chavista can hope for. He has strong negotiating skills and in a nation bitterly polarized, reconciliation is a high priority. In Miranda he has impressed his adversaries by refusing to politicize the state bureaucracy.

The nationalistic left-wing party Patria Para Todos (Nation for All) is now supporting him, in part because he has had some success in reforming education. If he wins on Sunday and in the general election, it is expected that he would try to restore independence to Venezuela's institutions and free Mr. Chávez's political prisoners.

It is difficult to imagine Mr. Chávez letting any of that happen. But a happy democracy can't be plopped down on a nation. It requires work. Sunday may be a start.