“Nobody said it was going to be easy” is the campaign slogan that Venezuelan opposition leader Henrique Capriles Radonski chose for the presidential election next October, and that remains true. Taking on incumbent President Hugo Chavez, an accomplished populist and self-styled revolutionary, is a tall order: for 13 years, he has seen off all comers. But it is getting easier.

It’s too early to write Chavez’s political obituary, but he is not a well man. Only a year after he had a cancerous growth removed from his abdomen, and despite four bouts of chemotherapy, he is back in Cuba for further treatment. Another tumor has been cut out from the same location, and this time he will require radiation therapy. The signs are not good.

“I swear that I’ll live and I’ll accompany you to new victories,” Chavez told a rally in Caracas the day before he left for Cuba. “No cancer will stop us.”

If sheer willpower and old-fashioned Marxist rhetoric were enough, Chavez would still be ruling Venezuela 20 years from now, but he actually has to win elections to stay in office. He controls all the levers of state power and he bends the electoral rules shamelessly, but in theory he could be voted out. If he has not visibly recovered his health and his strength by October, he probably will be voted out.

For the first time since Chavez won power, all the opposition parties have united behind a single candidate. Capriles is an energetic challenger 18 years younger than Chavez, and he has the wit not to trade insults with the older man, who is a master of vitriolic abuse.

Chavez recently called his rival “a pig,” but Capriles simply replied: “I wish the head of state a long life. I want him to see the changes that are going to come about in our country, for him to see a Venezuela of progress, a united country, a country where Venezuelans have many opportunities.” He makes Chavez’s rhetoric sound dated and vicious, as indeed it is.

If Venezuela’s politics were a simple matter of the poor against the rich, then Chavez would win every election hands down, for the poor certainly outnumber the rich. In reality, however, the opposition parties won a narrow majority of the popular vote in the 2010 parliamentary elections.

The last opinion poll of Venezuelan voters, taken just before Capriles was chosen as the joint opposition candidate in a Feb. 12 primary, found a gap of less than 5 percent between Chavez and the still undetermined winner of the opposition vote.

The choice of Capriles will certainly erode Chavez’s lead further. He is a moderate politician firmly rooted in the principles of the modern South American center-left. As the governor of Venezuela’s second most populous state, Miranda, he has built up a reputation for fairness and efficiency, and he was already making Chavez look like a political dinosaur. He now seems to be a very sick dinosaur as well.

If Chavez were to regain his health in a couple of months, he would still have a good chance of defeating Capriles at the polls, for he is a formidable campaigner who can still mesmerize huge numbers of the country’s poorest people. If he becomes a feeble, absentee campaigner with what voters perceive to be a limited future, the vote will go the other way, and Capriles will win.

Chavez has allowed no obvious successor to emerge in his party, so that could be the end of the country’s long experiment in populist politics. If Capriles wins, he can then use Venezuela’s soaring oil revenues to continue Chavez’s anti-poverty programs and consolidate his hold on power. At least, he could do so if Chavez is willing to accept electoral defeat.

Nobody would have been willing to bet on that a year ago, but if the impression persists that Chavez is on his last legs, the hard-liners in his party will be reluctant to carry out a constitutional coup and risk ending up in power without him. This may really be the end of South America’s most colorful and controversial politician.

Gwynne Dyer is a London-based independent journalist whose articles are published in 45 countries.