“My gut feeling is that the PAN will be prepared to negotiate,” said Carlos Elizondo Mayer-Serra, an Oxford-trained political scientist at the Center for Research and Teaching in Economics, a Mexico City research center. “They need each other.”

The PAN “becomes the pivotal party,” Carlos Ramirez, an analyst with the Eurasia Group, a global risk-consulting firm, wrote in a report Monday. “Yet the PAN will not accede easily to the PRI’s wishes even in cases where there might be some policy agreement; the memory of 12 consecutive years of PRI obstructionism during PAN administrations will not disappear quickly.”

Deep political and economic restructuring, such as a move to boost low tax revenues and to apply value-added taxes in areas including foodstuffs, is considered crucial to giving the state tools to govern effectively.

Elizondo said many of Pena Nieto’s promises during the campaign would be swept under the rug.

“Elections in Mexico are more flexible in terms of promises,” he said. “Some of them will be forgotten very quickly, and some will have a cosmetic solution.”

Among his promises, Pena Nieto pledged to increase spending on science and technology to 1 percent of the nation’s economic output, halt increases in basic food prices and lower some electricity rates.

If he and his party find it hard going to win coalition support, the president-elect may have a natural explanation.

“He’ll play a blame game, which is, ‘Hey, I proposed a decent reform but these guys are just obstreperous,’ ” Estevez said.

Estevez differed with other analysts, saying he thinks that Pena Nieto will seek broader alliances with the PRD than with the center-right politicians.

“He’s going to govern with the left. This is going to be a center-left government,” Estevez said.

But Ramirez said the left was dead-set against opening the oil sector and on weakening the Pemex oil-workers union.

Such a position “only reinforces our long-held view that Pena Nieto is likely to move cautiously on his reform agenda, and prioritize other reforms ahead of a proposal to open the energy sector,” Ramirez wrote.