Former Mexico City Mayor Marcelo Ebrard is splitting with the country's leftist Democratic Revolution Party, or PRD.

Ebrard writes in a letter of resignation that he disagrees with party leadership's increasing closeness to President Enrique Pena Nieto and the governing Institutional Revolutionary Party.

He says he was a member of the PRD for 10 years but its current direction "is incompatible with the objectives and political duties of the Mexican left."

Ebrard joins a string of other prominent figures to part ways with the PRD. He has clashed with an ascendant faction known as the New Left, and last week was denied a party nomination for legislative elections in June.

Ebrard tweeted a photo of his resignation letter Friday. He was the capital's mayor from 2006 to 2012.