Latin populists are surging again.Obviously the U.S. midterm elections stole most people’s attention this week, but several important events in Latin America may have consequences almost as far-reaching, at least for the region itself.First, with no apparent warning, Argentina’s past and expected future president, Néstor Kirchner, died of heart failure, throwing his country’s politics into disarray. He was scheduled to enter the ring in the presidential tag-team contest that his wife, Cristina Fernández, and he had organized for 2011; instead of subjecting her to a bruising reelection battle, the idea was for him to run (and win, of course)—thanks to his complete control of the old Peronist machinery, including unions, governors, pension funds, state-owned banks, etc. Now she will have to run herself. Her popularity has risen from terrible lows a year ago, and there will be a sympathy vote for a widowed incumbent, but there are also threats on the horizon. These are mainly the investigations into accusations of corruption against the presidential couple, and that will now be a tempting instrument not only for the Kirchners’ opposition but also for friendly fire: Peronist rivals to Cristina Fernández, who might not have dared to take on her husband but also for friendly fire: Peronist rivals to Cristina Fernández, who might not have dared to take on her husband but do not fear his widow.Second, there are many in Argentina and abroad who sincerely believe that while Fernández did build a political career of her own, the conceptual and political horsepower came from her husband and that she was at best a sporadically eloquent spokesperson. These observers believe, with some grounds, that absent Néstor Kirchner, she will encounter great difficulties, and the Kirchner era will come to an end soon. This scenario is not implausible, and sympathy for the deceased does not last forever (except in the case of Perón himself). This would alter the geopolitical balance in Latin America, since for all practical purposes the Kirchners have been stalwart supporters, though perhaps not disciples, of the Bolivian Alternative for Latin America, which links Castro to Hugo Chávez to Evo Morales, Daniel Ortega, and Rafael Correa in a left-wing alliance.The Bolivian Alternative may replace its Argentine loss with a Brazilian gain. Dilma Rousseff, Brazil’s soon-to-be president, was elected on Luis Inácio Lula da Silva’s coattails and is widely seen as his political heiress. Her victory carries an enormous symbolic impact as Brazil’s first woman president. But she may not end up being as moderate and modern as Lula. She comes from a classically populist strain in Brazilian politics, a follower of Leonel Brizola, the charismatic governor of Rio de Janeiro and Rio Grande do Sul, who was much more of a nationalist, statist politician than a leftist union leader like Lula. She also lacks Lula’s control of their party, the Workers’ Party, and will either need her mentor to watch over them or will cave in to their demands, which Lula never did. Despite his penchant for grandstanding, Lula was a pragmatist. It would be surprising indeed if Rousseff did not prove more ideological, nationalist, and perhaps populist in economic and foreign policy. This will also alter the balance in Latin America.Finally, after Chávez’s legislative electoral defeat in Venezuela last September, he has begun another crackdown on his opposition. He nationalized (without compensation) an American-owned glass manufacturer that supplies bottles to the Polar Beer company, and the Polar Beer company in turn is said by Chávez to supply much of his opposition with funding and support. Goons, purportedly associated with the government, kidnapped and shot three leaders of the Venezuelan business organization Fedecámaras two weeks ago, and as feared, Chávez has lashed out against the main victors of the September elections. María Corina Machado, founder of an electoral-watchdog group, SUMATE, won more votes than any other candidate for Congress; her parents’ business, formerly a prosperous Venezuelan steel company, the second biggest in the country, was expropriated last week by Chávez, again, with no compensation. There is little doubt that this was at least partly a form of reprisal.So where do these momentous events leave Latin America? Given a weakened Barack Obama, who was never especially engaged in Latin America beyond photo ops and symbolism, these trends may counter what we had seen so far the last year. Electoral victories by pragmatic, centrist politicians like Chile’s Sebastián Piñera and Colombia’s Juan Manuel Santos may have been only a brief interlude before a return of radical populism to the region. That promises even more problems for Obama.Castañeda is a former foreign minister of Mexico, Global Distinguished Professor at New York University.