A breakaway group of traditionalist Catholics is set to consecrate four bishops next week despite Pope Leo XIV’s pleas for it to back off, deepening a confrontation the Vatican has warned could formally breach church unity.

The Society of St. Pius X (SSPX), a long-time opponent of reforms associated with the Second Vatican Council and known for its embrace of the traditional Latin Mass, plans a four-day event at its seminary in Econe, Switzerland. Vatican officials have described the consecrations as an intentional rupture of communion with Rome and said they would incur automatic excommunication for the bishops involved and for the bishop administering the rite under church law.

In a last-ditch letter, Pope Leo XIV urged the SSPX’s superior, Rev. Davide Pagliarani, to “turn back,” calling the planned action a sin of extreme gravity. The Vatican said the pope’s offer of dialogue remained open, arguing that going forward would harm the spiritual well-being of the group’s faithful, including by depriving them of licit—and in some cases even valid—reception of sacraments.

Pagliarani responded by saying the society did not want to separate from the Roman Church and framed its actions as support for Catholics who, in its view, need extraordinary assistance.

The Vatican and the group are both drawing on the wider history of the SSPX’s schism: in 1988, the group’s founder, Archbishop Marcel Lefebvre, consecrated four bishops without papal consent, and the Vatican excommunicated those bishops at the time. Though those original excommunications were later lifted as part of outreach efforts, Vatican officials have said the new consecrations would again follow the logic of that earlier rupture.

The showdown is also landing as Pope Leo XIV is trying to stabilize relations with traditional Catholics after divisions that worsened during Pope Francis’s pontificate, including restrictions that angered some conservative Catholics who preferred the older Latin liturgy.

Other traditionalists—some loyal to Rome—have criticized the SSPX plans as unlawful disobedience, while also expressing concern about how the Vatican has handled traditionalist disputes. Meanwhile, SSPX leaders have signaled that, even if consequences follow, they intend to proceed exactly as planned.