By Eric Marrapodi, CNN Belief Blog Co-Editor

Washington (CNN) - The charges ranged from promoting “radical feminism” to espousing religious teachings out of step with the Catholic Church. Now, six weeks after many American nuns said they were blindsided by a bruising Vatican assessment, a key nuns' leadership group is meeting to decide how to respond.

The board of the Leadership Conference of Women Religious, which represents the leadership of the vast majority of the nation’s nuns, began a four-day meeting in Washington on Tuesday, with church watchers dissecting the 22-member board's every move.

It's a fight that pits church men and against church women, and it could have broader implications for the global church.

One side is pushing the nuns to fight back against a church that they think has lost its way. The other is championing the Vatican against a group of aging nuns whom they say are on the verge of extinction unless they reform.

The powerful Vatican office, the Congregation of the Doctrine of the Faith, launched an investigation for several years. It issued a report in April charging that America's nuns had largely gone rogue, warning that the American nuns could be a negative global influence on the church.

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The Vatican report said that at an annual gathering of the Leadership Conference of Women Religious, guest speakers who preached "radical feminism" went unchallenged. The report also alleged sins of omission, saying the nuns were too focused heavily on social justice and not enough on opposing abortion, euthanasia and same-sex marriage.

Many nuns have publicly chafed at the report.

"For myself, the shock made me numb at first, and then I was profoundly sad that my life as a woman religious and my commitment to serving the poor would be so denigrated by the leadership of our church," says Sister Simone Campbell, who heads NETWORK, a liberal advocacy group in Washington. "All we do is work for love."

For the report to say "you don't do everything," Campbell says, is "ridiculous."

Some in the pews seemed to agree with that sentiment, even staging small protests across the country to support the nuns. During a recent stop at Campbell’s office, she showed CNN cards and letters of support.

The Vatican office that issued the assessment said it was a first step in reforming American nuns. “The renewal of the Leadership Conference of Women Religious," the report says, "… is the goal of this doctrinal Assessment."

Pope Benedict XVI, a theologian by training, was the head of the Congregation of the Doctrine of the Faith for decades before he was elevated to papacy. In interviews conducted while he held that earlier post, he spoke often about growing the church by pruning - becoming smaller but more devout before expanding.

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“Maybe we are facing a new and different kind of epoch in the church’s history where Christianity will be characterized more by the mustard seed, where it will exist in small, seemingly insignificant groups that nonetheless live an intensive struggle against evil and bring the good into the world-that let God in,” he told Peter Seewald in an interview for the book, "Salt of the Earth: Christianity and the Catholic Church at the End of the Millenium."

That vision has support from ardent Catholics.

"Far from a crackdown, the Vatican is asking the LCWR to prayerfully return to their roots and to the reasons their religious institutes were founded,” says Raymond Arroyo, a host on the Catholic Cable Channel EWTN.

“These monasteries were not founded 100 or 200 years ago to picket and contradict church teaching or the bishops," he says. "They were founded to faithfully serve brothers and sisters throughout society in the spirit of Christ."

The Leadership Conference of Women Religious is a group of 1,500 nuns who lead over 300 religious orders. Together, its members represent 80% of the 57,000 nuns across the United States.

Church experts say that the nuns have a few options in responding to one of the most powerful offices in the church. They could accept the assessment, negotiate or resign en masse and form a new group outside the watchful eye of the Vatican.

In a statement, the group said it would conduct this week’s special meeting “in an atmosphere of prayer, contemplation and dialogue and will develop a plan to involve LCWR membership in similar processes.”

“The conference plans to move slowly, not rushing to judgment," the statement said. "We will engage in dialogue where possible and be open to the movement of the Holy Spirit."

Even before the controversy broke, the Leadership Conference of Women Religious was already thinking seriously about its future with the church.

Nuns in the conference had long ago removed their habits and shifted away from the traditional roles within church structures, like working in parochial schools and hospitals. Today you are more likely to find a nun in contemporary dress at a soup kitchen than in a full habit cracking a ruler over a grade-schooler's knuckles.

But the leadership conference is shrinking as it ages.

“They’re certainly not getting new vocations, new members, at the rate they had been before the Second Vatican Council,” says Kathleen Cummings, associate director of the Cushwa Center for the Study of American Catholicism at the University of Notre Dame. “Since the late 1960s, their numbers have declined dramatically.”

The median age of American nuns is 70, she says, noting that career opportunities once available only to nuns inside the structure of the church are now open to women outside the church.

“Changes for women in America have far outpaced changes for women inside the church,” Cummings says.

The Leadership Conference of Women Religious once represented nearly 100% of the nation’s nuns. In the 1990s, though, a number of orders broke away and formed the Council of Major Superiors of Women Religious, returning to many of the older traditions of religious life, including wearing the habit.

The Council of Major Superiors of Women Religious is growing at a faster rate than the leadership conference, but Cummings said the numbers of new vocations there are “miniscule” as well.

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While leadership conference nuns viewed the evolving role of women to give them more of a social justice focus, Cummings says that "Vatican officials, and many Catholics, too, see those changes as startling and disturbing.

“What’s happening here with the doctrinal assessment is just the latest, and will have the most lasting effects, of a Vatican attempt to reassert the power they traditionally held over women’s religious life," Cummings says. "Power that they lost a lot of over the last 50 years.”

But conservative Catholics say the groups that are most beholden to that power are the ones that are growing.

“Some communities are clearly doing something right, others are moving to extinction,” says Arroyo. “Bottom line: a faithful witness is attractive and undeniably draws young people.

"The Vatican is throwing a life line to the leadership of female communities that are not thriving and attempting to facilitate a reform that will allow them to rediscover their initial calling and draw young vocations into the future," he says. "That's not a crackdown, it's a seek-and-rescue mission."

As the sisters debate and pray on how to respond, they realize they are in the center of a broader global power struggle.

“What’s really at stake here, in the larger significance, is the future of the church,” says Sister Maureen Fiedler of the order of Sisters of Loretto, which is represented by the Leadership Conference of Women Religious. “Whether we’re going to go back to the old church before the Second Vatican Council.”

The leadership conference plans to announce its next steps in responding to the Vatican on Friday.