Tunisia's former prime minister and Ennahda Secretary-General Hamadi Jebali said on his Facebook page Thursday that he was stepping down from the Islamist party, citing disagreement with the party’s policies.
Jebali said that he had joined the movement in the early 1970s in the name of "freedom and justice" against "tyranny and corruption."
He spent many years in prison under the regime of Zine El Abidine Ben Ali, who was ousted in the 2011 revolution that launched the Arab Spring.
Jebali said Tunisia now faced "huge challenges," in particular the threat of a return to "tyranny and corruption."
"I chose to be among those activists eager to ensure the peaceful revolution triumphed ... I have great difficulty in remaining faithful to this position given the state of Ennahda today. I find myself no longer agreeing with its choices," he said.
In general elections in October, Ennahda was beaten by the Nidaa Tounes party and has decided not to field a candidate in the presidential election, whose second round is set for Dec. 21.
However, the party has not ruled out collaborating with Nidaa Tounes, despite that party's virulent anti-Islamist stance and the presence in its ranks of former Ben Ali regime officials.
Ennahda's position has been hard to swallow for some members of the party which was ruthlessly repressed under Ben Ali.
Jebali became prime minister in December 2011 after the country's first free elections that were won by Ennahda. He quit during the political crisis that followed the murder of prominent leftwing opposition leader Chokri Belaid in February 2013.