He has promised to bring competition and more government oversight to the telecommunications market, taking aim at the monopoly-like control by one of the richest men in the world, Carlos Slim Helú. Also in the president’s sights is the giant media company Televisa, which dominates broadcasting through four networks and would face renewed competition under a proposal that could lead to the creation of two new channels. And his government has jailed the boss of the teachers’ union, the largest in Latin America, on accusations of embezzlement as part of a sweeping move to wrest full control of the schools from it.

It remains to be seen how any of the changes will turn out; Mexico has a long tradition of bold, finely shaped laws that are ultimately watered down or simply not enforced. The telecommunications proposal passed one chamber of Congress late Thursday and is now headed to the Senate.

But it seems clear that Mr. Peña Nieto has banked substantial political capital and bolstered his popularity, which may add momentum to thornier changes he plans, including opening up the state oil monopoly, long a source of national pride, to private investment.

The teachers’ union, Mr. Slim, Televisa — the targets, in the minds of many Mexicans, are hard to cheer for.

“He is trying to gain credibility and popularity,” said Helena Varela Guinot, a political scientist at the Ibero-American University in Mexico City. “He is saying, ‘I am a president that gets results, this is a government that is efficient, takes risks and goes after the big problems,’ although it is not clear in reality if his reforms will achieve the desired results.”