VATICAN CITY — The Vatican has an unusual dilemma on its hands after nearly all the nuns in a tiny French religious order threatened to renounce their vows rather than accept the Holy See’s decision to remove their superior.

The sisters argue that the Vatican commissioners sent to replace their superior general, who is also the niece of the order’s founder, have no understanding of their way of life or spirituality. The Church’s conclusion — contained in a summary of its investigation provided this week to The Associated Press — is that the Little Sisters of Marie, Mother of the Redeemer are living “under the tight grip” of an “authoritarian” superior and feel a “serious conflict of loyalty” toward her.

The standoff marks an extraordinary battle of wills between the Vatican hierarchy and the group of 39 nuns, most in their 60s and 70s, who run homes for the aged in rural western and southern France. Their threat to leave comes at a time when the Catholic Church can hardly spare them, with the number of sisters plummeting in Europe and the Americas.

The unlikely revolt had been brewing for years but erupted in 2017, when the Vatican suspended the Little Sisters’ government and ordered the superior, Mother Marie de Saint Michel, removed. The Vatican says it took action after local church investigations in 2010 and 2016 found an excessive authoritarianism in her rule and serious problems of governance.

Details of her alleged abuses of authority haven’t been revealed. But within two years of her election as superior in 2000, six sisters had left, church officials say.

“The grave acts posed by Mother Marie de Saint Michel are denounced and the sisters are called to religious and responsible behavior,” the prefect of the Vatican’s congregation for religious, Cardinal Joao Braz di Aviz, wrote the nuns in July.

By then, Braz had already appointed a commissioner and two deputies to run the order. But the Little Sisters refused to accept them and kept Saint Michel in place in the mother house.

As the standoff escalated, 34 of the 39 nuns issued an extraordinary public declaration last month saying they had no other choice but to ask to be relieved of their religious vows.

“We are not making this sacrifice lightly,” they wrote. “We wish to remain in total communion with the Church but we cannot signify more clearly, or more painfully either, our incapacity in conscience to obey what we are commanded to do.”

Their plight has garnered sympathy. A French support group, the Support Association of the Little Sisters of Marie, claims to have gotten 3,900 signatures for an online petition demanding the immediate restoration of the central government of the order and removal of the commissioners.

“We are in a situation of blockage,” said Marcel Mignot, president of the support association.

The sisters downplay problems with their superior and say the real dispute is over their local bishop’s decision to split up management of their elder-care homes that had been merged in recent years. They say the bishop used his authority to impose an unjust decision on them without taking their views or the financial implications into account.

“This is about power,” Mignot said, referring to the bishop’s authority over diocesan orders.

The sisters have appealed his decision to the Vatican’s high court “so that the truth can be re-established, but Roman justice takes its time,” the sisters wrote their supporters earlier this year.

Their cherished community was founded in 1954 in Toulouse by Marie Nault, a woman who, according to legend, stopped her formal education at age 11 to work on the family farm but possessed such spirituality that she developed the stigmata — the bleeding wounds that imitate those of Christ on the cross.

Nault took the name Mere Marie de la Croix — Mother Mary of the Cross — and opened four communities in western and southern France which, in 1989, won approval from the bishop to become a diocesan institute of consecrated life.

Born in 1901, Mother Marie died in 1999 and her niece, the current ousted superior, took over a year later. She remains at the mother house in Saint-Aignan sur Roë, in western France. She had been due to step down after her term was up and a new superior was elected, but plans for the election are now in limbo, Mignot said.

The standoff with the Little Sisters comes amid a continuing free-fall in the number of nuns around the world, as elderly sisters die and fewer young ones take their place. The most recent Vatican statistics from 2016 show the number of sisters was down 10,885 from the previous year to 659,445 globally. Ten years prior, there were 753,400 nuns around the world, meaning the Catholic Church shed nearly 100,000 sisters in the span of a decade.

European nuns regularly fare the worst, seeing a decline of 8,370 sisters in 2016 on top of the previous year’s decline of 8,394, according to Vatican statistics.

The Vatican, in its conclusions about the case, said it believed that the majority of the Little Sisters “truly want to follow the Lord in a life of prayer and sacrifice.”

While lamenting the “tight grip” that the superior has over them, the Vatican’s congregation for religious orders told AP that most sisters had been kept in the dark about the management dispute over the elder-care homes — details that even the Vatican commissioners haven’t fully ascertained since they haven’t been able to access the institutes’ finances, the Vatican summary said.

In the past, the Vatican has not been afraid to impose martial law on religious orders, male or female, when they run into trouble, either for financial, disciplinary or other reasons.

St. John Paul II famously appointed his own superiors to run the Jesuits in 1981, some 200 years after Pope Clement XIV suppressed the order altogether. Pope Benedict XVI imposed a years-long process of reform on the Legion of Christ order and its lay branches after its founder was determined to be a pedophile. More recently, the Vatican named a commissioner to take over a traditionalist order of priests and nuns, the Franciscan Friars of the Immaculate.

Nevertheless, the standoff with the Little Sisters is unusual, said Gabriella Zarri, retired professor of history and expert in women’s religious orders at the University of Florence.

“It’s serious, but it’s also serious that these nuns would do such a violent act as to threaten to leave religious life,” she said. “It’s difficult to understand, other than perhaps because of their attachment to the charism of the founder” and her niece.

Sabina Pavone, a professor of modern history at the University of Macerata, said Catholic archives — especially from Inquisition trials — are full of cases of the Vatican taking action when religious superiors assume “tyrannical” powers over their devoted followers.

While many of the cases date to the period of tremendous growth of religious orders for women in the 1800s, she added, “we shouldn’t be surprised that you find them today” as well.