Michelle Obama said it was evident in her short visit to Haiti today that there is still "so much to do" to get the country back on its feet after January's devastating earthquake.
Obama, on the first stop of her first solo trip out of the United States as first lady, said it was important to come now because Haiti has reached a point when "the relief efforts are under way but the attention of the world starts to wane a bit."
"In order for Haiti to get back to where it needs to be, it's going to take the world continuing to invest, to partner, to show that sense of compassion," she said at the United Nations logistics center in Port-au-Prince.
The first lady said the relief efforts in Haiti have been more than just a U.S. effort, but a global effort.
"America has been a leader, but it has not been the only leader, by any close margin," she said.
Asked if she felt the aid money that Americans have contributed is actually reaching the Haitian people, Obama said yes.
"By all accounts, the Haitian people are very happy with the relief efforts," the first lady said. "Still, accountability is key. And, you know, I know that the governments are going to continue to work together.
"But I think that my sense is the Haitian people feel a deep appreciation for what the world has done, that's for sure," she said.
Obama arrived in Haiti today with little fanfare for a surprise visit aimed at highlighting the United States' continued commitment to Haiti.
The stop on her way to Mexico came a day after Haitians observed the three-month anniversary of the magnitude-7.0 earthquake that devastated their capital city and parts of surrounding communities.
"It's powerful. The devastation is definitely powerful," Obama said of her first impressions of the country.
Obama was joined in Haiti by Jill Biden, wife of Vice President Joe Biden. The two landed in Port-au-Prince late this morning and took a helicopter tour of the city, where hundreds of thousands are homeless, living in tents and under tarps.
After meeting with President Renee Preval and his wife, Obama and Biden visited the downtown Plas Timoun, or Children's Place, a program where children can work on art projects as part of a post-quake therapy program.
About 900 children ages 6 to 10 take part each day in the program, which was set up by Haitian first lady Elisabeth Debrosse, Haitian graphic artist and painter Philippe Dodard and a group of psychologists, educators and politicians shortly after the earthquake.
The program is geared to children living in tent cities, and, in addition to the art projects, which take place in buses, it provides them access to mental health services, sports activities, food and water.
About 90 percent of the schools in the Port-au-Prince area and 40 percent in the surrounding region were destroyed by the January earthquake.
The first lady and Biden were greeted by dozens of children singing "welcome" in English. Obama jumped right in and danced with the children and gave them high-fives when they finished.
Another group of children sang a song in Creole that said, "We are glad to see you, we say let's be happy."
Obama and Biden also visited the quake-damaged College Episcopal, a high school where at least 20 people were killed in the earthquake.
The goal was for Obama and Biden to acknowledge the work of the United Nations and international relief communities for the "the truly global effort underway to help Haiti," according to the White House.
Biden is scheduled to return to Washington today.
Obama, who has been somewhat of a homebody since coming to the White House, with relatively little travel on her public calendar, made the unannounced visit before her scheduled trip to Mexico this evening for a three-day visit.
While in Mexico, Obama, who does not speak Spanish, will be hosted by first lady Margarita Zavala at Los Pinos, the presidential residence in Mexico City.
Aides to Obama said the two first ladies have met on a number of occasions at the White House and abroad and they share "issues of mutual interest" and "a warm relationship."
The first lady's agenda for the three-day trip mixes policy and community outreach with cultural events and social time with Zavala. An Obama administration official said the first lady's trip is the kick-off to her international agenda, which will focus on engaging the world's youth in conjunction with President Obama's broader vision of global engagement.
Others see the trip also as a key example of the power of the position of first lady.
Anita McBride, who served as chief of staff to Laura Bush, said the trip launches Michelle Obama as an invaluable representative for the United States and her husband's administration.
"The first lady of the United States really is the best ambassador a president can have," she told ABC News. "It's the person who's closest to him and every country, when they receive a foreign visitor, when it's a family member of the president, particularly his wife, that's an honor bestowed on that country, that the American first lady would take the time to visit their country.
Myra Gutin, professor at Rider University and author of "The President's Partner: The First Lady in the Twentieth Century," said first ladies are afforded the freedom to have a public agenda and travel schedule of an elected official but at the same time, fly under the radar and escape the intense scrutiny that comes with public office.
Global Engagement Tops First Lady's Agenda
The White House goal seems to be for the first lady to inspire Mexican students, from elementary school up to college, to get involved in their local communities and make a difference. An administration official said the first lady's agenda fits in with the president's goal of not just engaging governments and leaders around the world but also engaging people and communities.
"The first lady will meet with young people who as we speak are solving challenges, leading organizations," in their communities, an official said. "That's the idea -- really highlighting the opportunity we have engaging young people. And this platform allows her to highlight the role young people have in social innovation and finding new solutions to problems."
The centerpiece of the first lady's trip will be a speech at the Universidad Iberoamericana, where she will address university and high school students from in and around Mexico City. Her message is meant to inspire the students to get involved in their communities and take leadership roles.
Obama administration officials said the trip provides the first lady the opportunity to reach out to a generation of young people who are moving into adulthood and into positions of responsibility in their communities, countries and the world and her message will focus on that transition.
"She's following a long line of tradition of our nation's first ladies who have used their platform not only on the domestic front but on the global front and are our nation's best diplomat," McBride said.
Former first ladies Hillary Clinton and Laura Bush were frequent world travelers, both with their husbands and on their own. Clinton visited 80 countries during her husband's two terms and Bush visited 77 countries in her eight years at the White House.
Michelle Obama visited nine countries last year with the president -- the United Kingdom, France, Russia, Ghana, Denmark, Norway, the Czech Republic, Italy and Germany.
Gutin said this trip casts the first lady as "more of a political partner" with the president because of the substance of the agenda.
"Some first trips have been ceremonial," Gutin said of previous first ladies and their ventures abroad. "This trip for Mrs. Obama seems to be more substantive."
The first lady will take the message of her speech and do her own outreach to local communities, first by meeting with teachers and students at a public school for low-income elementary school students and later by meeting with a group of young leaders, administration officials said.
First Lady Includes Cultural Sites on Agenda
The first lady has more flexibility to her schedule than President Obama has on a trip abroad -- no wall-to-wall bilateral meetings, no large summits with world leaders. The schedule allows the opportunity for the first lady to take advantage of the host country's cultural sites and spend more time engaging with locals.
"The beauty of the position itself -- there's so much flexibility to pick and choose what it is you want to do and advocate for that you do have freedom and flexibility to determine your schedule, where you're going to devote your time," McBride said.
Obama and Zavala will tour the Museo Nacional de Antropologia, which holds the largest collection of ancient Mexican pieces in the world.
Obama eased her way into an agenda in 2009, dabbling in some policy, but mainly focusing on getting her family adjusted to their new life in Washington.
This year she kicked off in earnest her signature domestic policy issue, the "Let's Move!" campaign aimed at ending childhood obesity, and she hit the road to talk about the administration's efforts to promote healthy eating and living.
Now she is taking her popularity and outreach abroad where McBride said she can be an asset to her husband.
"The president can't do everything. When the person that is closest to him can take the time and make the effort to develop relationships and contribute to the diplomatic dialogue, it's really important," McBride said.
Aides said the Mexico trip has been in the works for several weeks and while there will be future international travel, they did not announce where Obama's next trip will be.
Obama will have the opportunity to return the hospitality next month when she and her husband host President Calderon and his wife at a state dinner at the White House.