Michelle Obama on Haiti: “the attention of the world starts to wane a bit.”

MEXICO CITY — Aiming to keep a spotlight on the plight of earthquake-ravaged Haiti, first lady Michelle Obama and second lady Jill Biden made a surprise visit to Port-au-Prince on Tuesday before landing in Mexico’s capital and motorcading downtown.

“I think it was important for Jill and I to come now because we’re at the point where the relief efforts are under way, but the attention of the world starts to wane a bit,” Mrs. Obama said before she left Haiti. “And as we enter the rainy season and the hurricane season, you know, the issues are just going to become more compounded. And I think it was important for us to come and shed a light.”

Mrs. Obama and Mrs. Biden spent just over five hours in Haiti, taking a helicopter tour of the flattened city, where hundreds of thousands are still homeless. The two women also met with Haiti President Rene Preval, and his wife, Elisabeth; toured a high school destroyed by the Jan. 12 earthquake and stopped at a children’s camp and talked to U.N. employees.

Mrs. Obama offered her first impression of the ruins as she was speaking with Mrs. Preval. “It’s powerful. The devastation is definitely powerful,” she said.

Mrs. Obama’s plane landed at the Benito Juarez Airport in Mexico City just after sunset in a visit designed to underscore the close relationship between the two nations. Mrs. Obama’s airport greeters included about 50 young Mexican girls, members of “Las Guias,” sort of like the Girl Scouts, and 37 boys and girls were Red Cross volunteers. Mrs. Obama was wearing a sleeveless blue dress and flowing print skirt.

The Haiti trip was planned for weeks, but kept secret by the East Wing until Tuesday.

Even knowing this, the East Wing billed Mrs. Obama’s Mexico visit, to run through Thursday morning, as her first solo official foreign trip.