The Society of St Pius X (SSPX) plans to consecrate four new bishops without papal approval on July 1.
The Vatican has categorized these upcoming consecrations as a schismatic act, warning of automatic excommunication.
The SSPX justifies the move as a state of necessity to ensure the continued administration of traditional sacraments.
Pope Leo XIV has expressed regret over the decision but indicated that the church must continue despite these divisions.