Mexican Economy Minister Tatiana Clouthier stepped down Thursday after co-leading talks with the US and Canada to resolve a dispute over the Latin American country’s nationalist energy policies.

Clouthier tried to contain tears when reading her resignation letter during President Andres Manuel Lopez Obrador’s daily press conference, before quipping that the strain of the job including regularly attending the 7 a.m. briefings had worn her out.

“My capacity to contribute to the team is exhausted,” Clouthier, one of the centrist members of Lopez Obrador’s cabinet, said.

The dispute under the North American free trade deal filed by the US and Canada in July argues that Mexico discriminates against foreign companies trying to operate in the country. After 75 days of talks, the US and Mexico agreed to extend consultations this week, putting off the prospect of a dispute resolution panel for the time being.

Clouthier, together with Foreign Affairs Minister Marcelo Ebrard, was leading a team of top Mexican officials working to resolve the dispute.