Mexican officials and an honor guard of soldiers greeted Obama on the tarmac before he left for a private meeting with Peña Nieto at the National Palace, a hulking building in the center of the capital. Onlookers snapped photos as the motorcade zipped through normally snarled streets.
Obama and Peña Nieto, who took office in December, are scheduled to hold a joint press conference after their meeting.
Mexico's youthful, telegenic president has promised broad reforms in education, banking and energy, as well as a strengthened federal government. U.S. officials are monitoring how these changes affect American interests.
One shift already has caused tension with Washington: Peña Nieto's administration has begun to restrict broad U.S. involvement in some counter-narcotics and other security operations, perhaps signaling the end of a period of close cooperation in law enforcement and intelligence.
Obama told reporters Monday that he would not judge Peña Nieto's move "until I've heard directly from them to see what exactly are they trying to accomplish."
"We've made great strides in the coordination and cooperation between our two governments over the last several years," Obama said. "But my suspicion is ... that things can be improved."
Obama's trip is aimed at highlighting economic progress and potential in Latin America, not security or immigration.
In a speech to Mexican students Friday, Obama is expected to tout increases in educational exchanges, increased trade opportunities and the reform package Peña Nieto has already passed.
The portrait of a Mexico “on the rise,” as one U.S. official put it, is disputed. Not all economic indicators are so rosy. But the upbeat message serves Obama’s top domestic priority: passing an overhaul of the nation’s
More than half the immigrants in the U.S. who crossed the border illegally or overstayed their visas are Mexicans. If Obama can assure U.S. lawmakers, and their constituents back home, that the poverty and violence that caused illegal immigration are easing, he may have an easier time winning support for the bill.
"Economic development in Mexico will also ultimately get at the root cause of illegal immigration to the United States, so that's another benefit of the economic growth underway in Mexico," said Ben Rhodes, a deputy national security advisor.
Obama will take a similar message to Costa Rica on Friday and Saturday, when he will meet with several Central American leaders.