MEXICO CITY -- When Enrique Pena Nieto assumes Mexico’s presidency this weekend, he’ll return the once-entrenched Institutional Revolutionary Party to power with a strong breeze at its back.

After years of lackluster growth, Mexico’s economy hums once again. A mood of compromise has set in among often-fractious political parties. And crime groups have cut down on the atrocities that gave the nation a black eye in recent years.

“He’s got the stars aligned in his favor,” said Jorge Zepeda Patterson, an economist and political analyst.

Five months after a triumph that was narrower than expected, the former state governor takes office Saturday. Behind his rise is the Institutional Revolutionary Party, known as the PRI, the political party that ruled Mexico with a colossal grip for 71 years until an election loss in the year 2000.

A party with sprawling tendencies, the PRI’s umbrella covers a disparate lot that ranges from technocratic modernizers to old guard nationalists who controlled the levers of power in what was once termed the “perfect dictatorship.”

Pena Nieto has set forth a broad reform agenda that could upend some of the cornerstones of previous PRI governments, such as opening the state Pemex oil company to outside investment and undertaking strong tax and fiscal reforms.

Some of Pena Nieto’s fiercest resistance may come from within his party.

“He has to be very careful with how he deals with the PRI governors, with the PRI unions, with the PRI old guard, and although he’s skillful and very intelligent . . . he’s going to have to take a lot of these people into account,” said Jorge G. Castaneda, a former foreign minister.

Mexico, however, is a different country than when the PRI last ruled. Civil society groups began to flourish over the past 12 years, the media has grown accustomed to freedom, and different branches of government are taking their roles more seriously.

Forces outside the party may help weaken resistance to reforms.

“Pena Nieto may become a democratizing force even without really wanting to be one,” said Zepeda, whose column appears on the sinembargo.mx news website.

When the PRI handed over the reins of the country in 2000, the strong presidentialist system in Mexico fractured. Under the center-right National Action Party, Mexico passed through a vacuum of power of sorts as legislators blocked initiatives, governors evolved into regional political kingpins, union bosses strengthened their fiefdoms and crime groups tore into one another.

Even monopolistic conglomerates – among them the telecommunications empire led by Carlos Slim, the world’s richest man – grew weary of a lack of clear rules.

“Groups of power in the country are increasingly in search of a kind of overall referee,” Zepeda said. “The feeling is that this mutual war between groups to fill the vacuum has started to generate inefficiencies. . . .”

“There is a feeling that we need . . . a more executive president. Even before Pena Nieto moves a finger, there is a favorable environment to push through changes.”

In a trip to Washington and Ottawa this week, Pena Nieto indicated he would broaden the international agenda beyond issues of security and migration to push for deeper economic integration in energy, trade and other areas.