Doug Coe, an influential — if enigmatic — spiritual power broker who melded faith and politics as a convener of the annual National Prayer Breakfast, weekly prayer sessions for the Washington elite, and an international ministry that drew critics as well as acolytes, died Feb. 21 at his home in Annapolis. He was 88.

The cause was complications from a heart attack and a stroke, according to a statement provided by a family spokesman, A. Larry Ross.

In a city where most notables seek rather than shun the spotlight, Mr. Coe was a conspicuous exception. In 2005, when Time magazine named him one of the 25 most influential evangelicals in the United States, he declined to provide a picture to accompany the article.

Described as “the stealth Billy Graham,” the evangelist with an international following, Mr. Coe rarely granted interviews, leaving public attention to the presidents, members of Congress and other potentates to whom he ministered as a layman.

They included former president George H.W. Bush, who commended him for his “quiet diplomacy,” and Hillary Clinton, the former first lady, U.S. senator and secretary of state, who described him in her memoir “Living History” (2003) as “a source of strength and friendship” and “a unique presence in Washington: a genuinely loving spiritual mentor and guide to anyone, regardless of party or faith, who wants to deepen his or her relationship with God.”

Mr. Coe died Feb. 21 at 88. (A. Larry Ross Communications)

“I think Doug Coe may be the single individual who had the largest influence on the spiritual awakenings of global leaders over the last 25 years,” D. Michael Lindsay, the author of “Faith in the Halls of Power: How Evangelicals Joined the American Elite” (2007), said in an interview. “In much the same way that Billy Graham reached the multitudes, so Doug Coe reached the upper levels of power and influence,” Lindsay said, challenging leaders “to be more generous, to be more giving, to act on their faith.”

The secrecy that enshrouded Mr. Coe’s organization — formally the Fellowship Foundation but better known as the Fellowship or “the Family” — enticed detractors to compare the group with a shadowy cult.

It reportedly ran as many as several hundred ministries domestically and abroad. Of those activities, only the prayer breakfast was widely publicized. That event was as prominent as the Fellowship’s other undertakings were secretive: The breakfast, inaugurated in 1953, has been attended by every president since Dwight D. Eisenhower.

In the past decade, the Fellowship drew unflattering attention after several politicians it had embraced — among them former senator John Ensign (R-Nev.) and former governor and now Rep. Mark Sanford (R-S.C.) — confessed to extramarital affairs. A house on C Street SE in Washington, owned by a Fellowship affiliate and rented to a bipartisan group of legislators who participated in Fellowship activities, was described in the New Yorker magazine as a “frat house for Jesus.”

An investigative journalist, Jeff Sharlet, documented what he alleged to be the Fellowship’s theocratic ambitions in two books “The Family: The Secret Fundamentalism at the Heart of American Power” (2008) and “C Street: The Fundamentalist Threat to American Democracy” (2010).

Among other accusations, Sharlet charged that the Fellowship helped push a legislative effort in Uganda to make acts of homosexuality a capital offense. A Fellowship member, J. Robert Hunter, told the New York Times that numerous Fellowship members had spoken out against the legislation.

Sharlet also noted the group’s contact with strongmen including Omar al-Bashir of Sudan, who is accused of committing war crimes in the Darfur region.

“Most of my friends are bad people,” Mr. Coe told the New Yorker in 2010, in one of the few interviews to which he consented. “They all broke the Ten Commandments, as far as I can tell.” But, he remarked, “Jesus even met with the Devil.”

According to Lindsay’s book, the Fellowship was regarded in some circles as an “underground State Department,” playing roles in the 1978 Camp David Accords between Egypt and Israel and the brokerage of a peace agreement between Rwanda and Congo in 2002.

Domestically, the Fellowship wielded much of its influence through the weekly bipartisan prayer groups that it organized for U.S. senators, members of Congress and other government leaders.

Participants were ensured total confidentiality so that, while shouldering the weight of power, they could unburden themselves of their private fears and troubles.

“We’re not being secretive, it’s just that no one advertises that we’ve got a guy here who’s an atheist and is having a problem with his life, or maybe stole money from his country’s treasury,” Mr. Coe told the New Yorker.

Michael Cromartie, vice president of the Ethics and Public Policy Center in Washington, said in an interview that politicians trusted Mr. Coe “because he wasn’t immediately going out and saying, ‘I met with senator so-and-so.’ ”

“That was a virtue,” Cromartie added.

Douglas Evans Coe was born in Medford, Ore., on Oct. 20, 1928. His father was Oregon state superintendent of schools. A grandfather was a circuit-riding preacher in Alaska, and a grandmother was a missionary to the local indigenous population.

Mr. Coe received a mathematics and physics degree from Willamette University in Salem, Ore., in 1953. Mr. Coe said that, despite his family’s religious traditions, and despite prodding from his mother, he discovered his faith slowly.

“For me to think that a baby born two thousand years ago to a fifteen-year-old girl in Bethlehem created the solar system — that didn’t make any sense to me,” he told the New Yorker. Furthermore, he said, “I just couldn’t figure out a God that would send everybody to Hell except a few of my friends, and my mom and my dad.”

While studying at the university, he developed a newfound religious fervor, inspired in part through Graham’s teachings. He joined Christian groups including Young Life. Through Mark Hatfield — then a Willamette professor and later a Republican senator from Oregon — Mr. Coe met Graham and participated in his “crusades,” as they were known.

Another key influence was Abraham Vereide, a Methodist minister who founded a national movement of prayer breakfasts for civic leaders, including what became the annual event in Washington. Mentored by Vereide, Mr. Coe took over his leadership of the movement after Vereide’s death in 1969.

Mr. Coe traveled widely for his ministry, most recently to the Pitcairn Islands in the South Pacific and the Principality of Andorra, according to Ross.

Mr. Coe’s survivors include his wife of 68 years, the former Janice Muyskens of Annapolis; five children, Debbie Burleigh, Becky Wagner, David Coe and Timothy Coe, all of Annapolis, and Paula Corder of Arlington, Va.; 21 grandchildren; and 56 great-grandchildren. His son Jonathan Coe died in 1985.

Sarah Pulliam Bailey contributed to this report.