More than one-third of Iran’s Parliament resigned Sunday to protest a sweeping ban on candidates running in the parliamentary election later this month. The defiant move threatened to plunge Iran’s political system into chaos.

One by one, angry lawmakers who have held a three-week sit-in at the huge Parliament building, marched up to the podium and handed their resignations to the speaker. In an emotional statement read aloud during the session of Parliament on Sunday and broadcast live across the nation on Iranian radio, the members who resigned accused powerful conservatives of seeking to impose a religious dictatorship like that of the Taliban.

The mass resignation coincided with what was supposed to be a day of national celebration, the 25th anniversary of the return to Iran of Ayatollah Khomeini from exile in France.

The resignations came a day after the president announced that his negotiations with senior religious officials had failed to resolve the crisis.