WASHINGTON (AP) — President Barack Obama pledged to stand with Mexico against "the scourge of violence and the drug cartels" as he met Tuesday with President Enrique Pena Nieto amid concern over the unsolved abduction of 43 Mexican college students last September.

Protesters in front of the White House questioned what happened to the students who are presumed dead, allegedly at the hands of local officials and police in league with a drug cartel. The dozens gathered in the city's first winter snowfall were a smaller version of the massive street protests that have occurred in Mexico calling for Pena Nieto's resignation.

The case has come to signify an engrained abuse of authority and corruption in Mexico, and sparked indignation that federal authorities took 10 days to intervene. Pena Nieto has drawn criticism for saying it was time to "move beyond" the case just weeks after their abduction and taking a month to meet with their families.

Obama was under pressure from groups including Human Rights Watch and the AFL-CIO to press Pena Nieto to take the case more seriously. Mexican officials initially said they did not expect Obama to raise it, but he did by pledging U.S. support.

Obama told reporters in the Oval Office that Americans have been following the "tragic events surrounding the students whose lives were lost." He said Pena Nieto described reforms he's initiated around the issues that were raised.

"Our commitment is to be a friend and supporter of Mexico in its efforts to eliminate the scourge of violence and the drug cartels that are responsible for so much tragedy inside of Mexico," Obama said. But, he added, "Ultimately it will be up to Mexico and its law enforcement to carry out the decisions that need to be made."

Pena Nieto responded by thanking Obama for working with Mexico to improve security, "especially this clear challenge Mexico has to continue fighting organized crime."

Pressed later on whether the Obama administration believes that the investigation in Mexico has been credible, White House press secretary Josh Earnest pointed out that arrests have been made and the probe continues. He said Obama stands with Pena Nieto as he tries to put reforms in place.

The protesters across the street in Lafayette Park were so boisterous they could be heard by people in the Oval Office during the presidents' meeting. The Oval Office is on the other side of the White House from the protesters in Lafayette Park.

"We are very upset," said Ivan Almonte, a 36-year-old Mexican who has been living in the United States for 16 years. "We want Pena Nieto to quit and to tell us where are the 43 students. Why so much silence?"

The students from a rural teachers college were taken by Iguala police Sept. 26 and allegedly turned over to members of the Guerreros Unidos drug gang that rules parts of the southern Mexican state of Guerrero. Iguala is a city that is southwest of Mexico City.

The Mexican government says the students were likely killed and their bodies incinerated beyond identification. Only one body has been found and identified.

Before the meeting a Pena Nieto aide, undersecretary for North America affairs Sergio Alcocer, raised the shooting of unarmed Michael Brown in Ferguson, Missouri, when asked about whether the students' abduction would be part of the talks. He said Mexican officials didn't expect it.

"We have cases of violence in different parts of the world," Alcocer said. "Within the United States, we know there has been this kind of violence in the area of Missouri, to mention just one case."

Pena Nieto praised Obama's executive action to shield from deportation some 4 million immigrants — most of them from his country — and his "very audacious decision" to re-establish diplomatic ties with Cuba after a half century of estrangement.

Obama said he hopes to approach Cuba with "a more constructive policy but one that continues to emphasize human rights and democracy and political freedom." He said he'll participate in the Summit of the Americas, a regional meeting, in April in Panama along with Cuba, but will insist that those topics are on the agenda.

Years of estrangement between the U.S. and the communist island nation off the Florida coast had long been a point of friction with Mexico and other Latin American countries that do business with Cuba.

"Mexico will be a tireless supporter of the good relationship between two neighbors," Pena Nieto said.

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Associated Press writer Luis Alonso Lugo contributed to this report.

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