Mexico’s presidential election produced a contradictory outcome: There was a clear-cut victory for the Institutional Revolutionary Party (PRI), which ruled Mexico for 70 years until 2000; a resounding defeat for the candidate of the outgoing National Action Party (PAN); and a surprisingly strong showing for the left’s contender, Andrés Manuel López Obrador. But behind these mixed results may lie a promising future for Mexico and its people.Enrique Peña Nieto, the PRI winner, obtained much less than a mandate, despite getting 3 million more votes than the runner-up. He failed to achieve a majority in either house of Congress, as Mexicans split their ballots, particularly in states where they seemed to punish PRI governors for the violence that has swept Mexico’s “badlands.” Those who fear a PRI restoration can rest assured: The new president will be constrained by Mexico’s recently acquired checks and balances.If the election was a referendum on the policies of outgoing President Felipe Calderón and his signature issue – the war on drugs – voters rejected continuity. This is not surprising after nearly 60,000 deaths, $60 billion in spending, egregious human rights violations and the terrible international image Mexico has acquired in the process. Josefina Vázquez Mota, the PAN candidate, received barely a quarter of the votes; the party lost former bastions such as Jalisco, which it had governed for 18 years, and was practically banished from the capital. PAN placed third in the lower house and roughly tied with the left in the Senate. A former party chairman and close friend of Calderón’s called the results a “disaster.”While many supporters of left-wing López Obrador are convinced that the election was rigged, he cannot mount much of a challenge. His claims, and those of students in the streets, that the vote was unfair because electoral laws allowed the media to take sides and permitted the powers that be to pour tens of millions into his opponents’ coffers ring false: The legislation was tailor-made for his party. Furthermore, the Federal Electoral Institute commissioners and justices who oversee election spending and media coverage were voted in by the left.Mexico is in an ambiguous situation: No one has a mandate, and the left is just short of being able to block constitutional reform in Congress. But there are plenty of areas of agreement between the PAN and Peña Nieto, and even between Peña Nieto and outgoing President Calderón, that needed reforms can be passed. So which will it be?On oil, for example, the left is opposed to changing current law; the PAN and Peña Nieto said during the campaign that they support a constitutional amendment allowing minority private investment in Pemex, the state-owned monopoly. On education, all three parties backed independent teacher evaluation and extending the elementary school day from four hours to eight. Perhaps most important, PAN and Peña Nieto came out in favor of a major overhaul of Mexico’s thin and tattered social safety net, one that would include a tax-based extension of health care, old-age pensions and unemployment insurance for all Mexicans. This would be Peña Nieto’s most ambitious reform, and he should seek and get PAN support for it.Finally, there is the war against organized crime. Peña Nieto and the PAN candidate called for two important changes in Calderón’s approach: first, concentrating scarce resources on combating violence – kidnapping, extortion, murder rates – instead of focusing on the capture of kingpins or interdicting drug shipments to the United States. Both also proposed overhauling Mexico’s police system, ramping up the federal contingent from about 30,000 to some 100,000 officers over three years. It’s the right idea, but not necessarily a ringing endorsement of the efforts by Calderón and the Obama administration to build a federal police force in Mexico.Which brings us to the election’s impact on Washington. If Peña Nieto can push through some reforms, Mexico will become a more prosperous, democratic and middle-class society; therein lies the United States’ real interest in Mexico. He can build on the notable successes his predecessors have achieved in health, housing, freedom, transparency and in combating poverty; American support would be important and welcome in these fields. So would U.S. cooperation in exploring alternative strategies to the failed war on drugs. On this score, just as Barack Obama and Richard Nixon would make strange bedfellows, so would Felipe Calderón and Enrique Peña Nieto.Castañeda, a professor at New York University, was Mexico’s foreign minister from 2000 to 2003, in the PAN government of Vicente Fox. This commentary was edited from the original, which appeared in The Washington Post.