IT IS a season of unrest in the Western Hemisphere. Venezuela and Nicaragua remain mired in sporadically violent crises brought on by the ineptitude and repression of their leftist governments. In Haiti, at least 30 people have been killed in recent protests against alleged government corruption in recent weeks, 15 of them by the police, according to the United Nations. Peru is in the midst of a power struggle between its president and Congress. Ecuador recently saw 11 days of upheaval, brought on by austerity measures required to get a $4.2 billion loan — and subsequently abandoned. Looting and arson erupted in Santiago, the usually calm capital of Chile, after a transportation fare hike triggered long-simmering anger over inequality.

Now, it is Bolivia’s turn. If anything, the demonstrations across that Andean country might be the most fateful, because they arise directly from the great historical vulnerability of Latin American democracies: alleged election fraud. On Sunday, President Evo Morales claimed victory in his bid for an unprecedented fourth term. Circumstantial evidence, however, suggested otherwise. Pre-election polls showed Mr. Morales’s main opponent, Carlos Mesa, in the lead. In the first official announcements, Bolivian electoral authorities reported the race was close enough to require a runoff between Mr. Morales and Mr. Mesa. Then the counting mysteriously stopped; when further results emerged, they had turned sharply in the incumbent’s favor. Mr. Morales has claimed outright victory, declared a state of emergency and accused his opponents of mounting a coup. All this, even though an Organization of American States observer mission in La Paz expressed “worry and surprise about the drastic and hard to justify change in the tendency of the preliminary results.” The State Department issued a similar message.

Mr. Morales came to power in 2006 as part of the wave of leftist victories that also made Hugo Chávez — with whom Mr. Morales forged a close alliance — Venezuela’s leader. Unlike Chávez, however, Mr. Morales managed the country’s hydrocarbon exports wisely and brought stability and growth to his country. Between 2006 and 2014, gross domestic product per capita doubled, and the extreme poverty rate has declined from 38 percent to 17 percent. Like Chávez, Mr. Morales has a strong demagogic streak and a will to power. In a 2016 referendum, voters denied Mr. Morales the right to run for a fourth term — but he pressed on anyway, armed with rulings from his hand-picked judiciary that said term limits were a human rights violation.

Economic and social progress under Mr. Morales had slowed in recent years, as prices for its export commodities fell and budget deficits ballooned. In short, the classic boom-bust cycle of Bolivia’s difficult history as one of the poorest countries in South America has reasserted itself. He has also been faulted for underreacting to fires in the Bolivian Amazon. Small wonder many Bolivians wanted to give Mr. Mesa at least a chance to face Mr. Morales one- on- one in a second round. Allowing a runoff, as the OAS recommended, is the option Mr. Morales would take if he does not, in fact, want to be seen as what the opposition calls him: a “dictator.” There is still time for Bolivia’s president to step back from the brink.

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