It’s not hard to explain why, after 71 uninterrupted years in power, Mexico’s Institutional Revolutionary Party lost the 2000 presidential elections. It earned its defeat through decades of authoritarianism, repression, injustice and corruption and, more recently, through a succession of economic crises that cost the country dearly. Poor PRI, as the party is known, it could no longer even fix elections.Yet now, just 12 years later, all available polls point to a PRI victory in Sunday’s presidential election. Has amnesia set in? Has multiparty democracy failed? Does the country really want to turn back the clock? Or has the PRI changed, as it loudly claims? And if it has changed, will it be any more capable of addressing Mexico’s problems than it was in the past? This much is clear: Mexicans have felt badly let down by 12 years of government by the conservative National Action Party, or PAN. Clean elections and a free press are now taken for granted, but corruption is still rampant, poverty is widespread, economic growth has been slow and an army-led “war on drugs” has resulted in a mind-boggling death toll of around 60,000 in less than six years. Not all can be blamed on Vicente Fox, the man who defeated the PRI in 2000, and his successor, the outgoing president, Felipe Calderón. Washington lost interest in closer ties with Mexico after 9/11. And Mexico’s deep economic dependence on the United States meant it suffered more than most countries from the post-2008 market crash (although things are now looking up). Domestically, plans for much-needed reforms of energy policy, the tax structure, labor laws and education were also frustrated. Since neither Mr. Fox nor Mr. Calderón enjoyed an absolute majority in Congress, the PRI and the leftist Party of Democratic Revolution, or PRD, cheerfully joined forces to block anything that smelled of modern capitalism. The “war on drugs,” though, was Mr. Calderón’s idea, launched, it seems, to show his teeth after his narrow — and perhaps questionable — electoral victory in 2006. But instead of defeating the cartels, it has brought violence on a scale unknown in Mexico since the late 1920s, albeit much of it between drug gangs. And even as drug capos go about murdering journalists and corrupting generals, Mr. Calderón has stood by his policy — with American backing. So, yes, Mexicans want change. But with the PRI? Strangely perhaps, in the past the PRI never actually ruled Mexico. It ran a skilled vote-gathering (or vote-fixing) operation, but the country was run by a political bureaucracy in league with other power centers, such as banks, labor unions, the army, television magnates and industrial moguls. The PRI provided a rubber-stamp Congress and, every six years, the outgoing president picked his successor. Over the past 12 years, even with PAN presidents in the National Palace, this broad power structure has remained largely intact. Further, a majority of Mexico’s 31 states have continued to be governed by the PRI machine and its all-too-familiar modus operandi. The only solid opposition stronghold has been Mexico City, which has been relatively well run under three successive PRD mayors. Without a president to name its candidate, then, for Sunday’s election, the PRI needed a fresh face who was also acceptable to the powers-that-be. Step forward Enrique Peña Nieto, until last year the PRI’s governor in the state of Mexico. At 45, he is too young to be tarred by the PRI’s darkest years. His good looks and actress wife also cast him in a different movie from his Don Corleone forebears. From the shadows, the PRI “dinosaurs” are cheering the makeover. The main challenger is the PRD’s Andrés Manuel López Obrador, the leftist former Mexico City mayor who claims he was robbed of victory in 2006 and who still terrifies the establishment. The PAN’s candidate, Josefina Vázquez Mota, a former education minister and the first woman to run for the Mexican presidency, was chosen against Mr. Calderón’s wishes but still shares blame for his failures. All three candidates have sprinkled the land with promises, but at least on the critical issue of drug-related violence, they concur that Mr. Calderón’s “war” is harming Mexico more than the cartels. Their answer is somehow to reduce violence. Fine, but how is this to be done without easing efforts to stop trafficking into the United States? Understandably Washington is nervous. A more central question is whether a “new” PRI will dare confront the near monopolies — in energy, telecommunications, finance, cement, food and television — that support its return to power and have long profited from the noncompetitive marketplace. Mr. Peña Nieto’s best suggestion so far is to open up the government-owned oil monopoly, Pemex, to some private investment, but that battle lies ahead. So can the PRI change its spots? Many Mexicans are deeply skeptical. Already during the campaign, tens of thousands of students demonstrated against a return to the worst of the past. But in truth I don’t think Mexico would now allow that to happen. A more likely scenario is that, if elected, Mr. Peña Nieto will try to please everyone and will disappoint many. And if he governs only for the PRI’s old pals, he can expect to hear from the Mexican street again. Alan Riding, a former reporter for The New York Times, is the author of “Distant Neighbors: A Portrait of the Mexicans.”