WASHINGTON - The Obama administration's senior diplomat for Latin America is stepping down, and the chairwoman of the House of Representatives Foreign Affairs Committee is happy to see him go.

The State Department said Friday that Arturo Valenzuela will leave in a few months to return to a teaching post at Georgetown University in Washington after serving since 2009 as the assistant secretary of state for Western Hemisphere affairs.

Spokesman Mark Toner said the administration will start looking for a successor, and it was deeply appreciative of Valenzuela's service.

Valenzuela's tenure was criticized, however, by Republican Ileana Ros-Lehtinen, who said he had not done enough to counter rising anti-Americanism in the region led by Presidents Hugo Chavez of Venezuela, Daniel Ortega of Nicaragua, Rafael Correa of Ecuador and Raul Castro of Cuba.

Valenzuela's time was "marked by abject failure by the US to stand up to the attacks against democracy and fundamental freedoms," the Cuban-born congresswoman said in a statement. "US interests have suffered as a result."

Valenzuela, an academic born in Chile and a veteran of the President Bill Clinton's administration, is announcing his resignation at a time when no US ambassador is posted to Mexico, Venezuela, Ecuador or Bolivia.

The announcement also comes before next week's visits to Washington by the presidents of Mexico and El Salvador, two US allies in the hemisphere.