(CNN) Evangelist Billy Graham -- a confidant to presidents, a guiding light to generations of American evangelicals and a globe-trotting preacher who converted millions to Christianity -- died Wednesday at the age of 99, his spokesman confirmed to CNN.

Graham passed away at his home in Montreat, North Carolina, spokesman Jeremy Blume said.

The skinny preacher with the booming voice evangelized to nearly 215 million people over six decades and prayed with US presidents from Harry Truman to Barack Obama.

Republican presidential candidate Mitt Romney speaks with Graham and his son Franklin during a visit to Montreat in 2012.

Republican presidential candidate Mitt Romney speaks with Graham and his son Franklin during a visit to Montreat in 2012.

US President Barack Obama meets with Graham at his Montreat home in 2010.

US President Barack Obama meets with Graham at his Montreat home in 2010.

Graham and his son Franklin attend the Metro Maryland Festival in 2006. The three-day program was led by Franklin.

Graham and his son Franklin attend the Metro Maryland Festival in 2006. The three-day program was led by Franklin.

Graham leads his "last crusade" at Flushing Meadows-Corona Park in New York in 2005. He spoke to more than 230,000 people.

Graham leads his "last crusade" at Flushing Meadows-Corona Park in New York in 2005. He spoke to more than 230,000 people.

Graham speaks to a crowd at Arrowhead Stadium in Kansas City, Missouri, in 2004. Over the course of his career, Graham preached to more than 215 million people in more than 185 countries and territories.

Graham speaks to a crowd at Arrowhead Stadium in Kansas City, Missouri, in 2004. Over the course of his career, Graham preached to more than 215 million people in more than 185 countries and territories.

Presidential candidate George W. Bush meets with Graham in Jacksonville, Florida, in 2000. Years earlier, Bush said, a conversation with Graham had helped lead him to give up drinking.

Presidential candidate George W. Bush meets with Graham in Jacksonville, Florida, in 2000. Years earlier, Bush said, a conversation with Graham had helped lead him to give up drinking.

Former first lady Nancy Reagan greets Graham at the gala dedication of the Ronald Reagan Building and International Trade Center.

Former first lady Nancy Reagan greets Graham at the gala dedication of the Ronald Reagan Building and International Trade Center.

In 1997, Graham gave the invocation at the second inauguration of President Bill Clinton.

In 1997, Graham gave the invocation at the second inauguration of President Bill Clinton.

Graham gestures as he speaks to a capacity crowd at Ericsson Stadium in Charlotte, North Carolina, in 1996.

Graham gestures as he speaks to a capacity crowd at Ericsson Stadium in Charlotte, North Carolina, in 1996.

Pope John Paul II meets with Graham at the Vatican in 1993. Graham had often been called the "Protestant Pope."

Pope John Paul II meets with Graham at the Vatican in 1993. Graham had often been called the "Protestant Pope."

Graham preaches in New York's Central Park in 1991. It was his first appearance in New York City since 1970. The crowd was estimated at 200,000.

Graham preaches in New York's Central Park in 1991. It was his first appearance in New York City since 1970. The crowd was estimated at 200,000.

Graham takes a boat ride with US President George H.W, Bush near Bush's summer home in Kennebunkport, Maine, in 1989.

Graham takes a boat ride with US President George H.W, Bush near Bush's summer home in Kennebunkport, Maine, in 1989.

Graham and his wife visit her birthplace in Huaiyin, China, in 1988. They were married for 64 years until her death in 2007.

Graham and his wife visit her birthplace in Huaiyin, China, in 1988. They were married for 64 years until her death in 2007.

Graham speaks at Liberty Bowl Memorial Stadium in Memphis, Tennessee, in 1978. Inclement weather had forced the crusade to the nearby Mid-South Coliseum, but when the clouds lifted, Graham went to the stadium to speak to those who could not get into the smaller indoor arena.

Graham speaks at Liberty Bowl Memorial Stadium in Memphis, Tennessee, in 1978. Inclement weather had forced the crusade to the nearby Mid-South Coliseum, but when the clouds lifted, Graham went to the stadium to speak to those who could not get into the smaller indoor arena.

Graham speaks to a crowd of 18,000 on the closing night of the Southern Baptist Convention in 1974.

Graham speaks to a crowd of 18,000 on the closing night of the Southern Baptist Convention in 1974.

Graham is flanked by US President Richard Nixon, left, and Vice President Spiro Agnew as they bow their heads in prayer in 1969. Graham was speaking at Nixon's inauguration.

Graham is flanked by US President Richard Nixon, left, and Vice President Spiro Agnew as they bow their heads in prayer in 1969. Graham was speaking at Nixon's inauguration.

Graham addresses an audience in 1967. He was frequently listed by Gallup as one of the "Ten Most Admired Men in the World."

Graham addresses an audience in 1967. He was frequently listed by Gallup as one of the "Ten Most Admired Men in the World."

Graham speaks to more than 5,000 US troops in Vietnam in 1966.

Graham speaks to more than 5,000 US troops in Vietnam in 1966.

Graham addresses the congregation at the opening of a 32-day London crusade in 1966.

Graham addresses the congregation at the opening of a 32-day London crusade in 1966.

Graham appears in the 1963 documentary "The World's Greatest Showman: The Legend of Cecil B. DeMille."

Graham appears in the 1963 documentary "The World's Greatest Showman: The Legend of Cecil B. DeMille."

Graham dictates a synopsis of his evening sermon into a tape recorder in 1962. Secretaries would then type the synopsis for distribution to the press. Graham was conducting an eight-day crusade in Fresno, California.

Graham dictates a synopsis of his evening sermon into a tape recorder in 1962. Secretaries would then type the synopsis for distribution to the press. Graham was conducting an eight-day crusade in Fresno, California.

Graham preached that racial segregation was unbiblical, but some civil rights rights leaders criticized him for not being more involved in the civil rights movement. Graham asked the Rev. Martin Luther King Jr. to deliver a prayer at a Madison Square Garden crusade in New York in 1957.

Graham preached that racial segregation was unbiblical, but some civil rights rights leaders criticized him for not being more involved in the civil rights movement. Graham asked the Rev. Martin Luther King Jr. to deliver a prayer at a Madison Square Garden crusade in New York in 1957.

Graham gets a kiss from his wife, Ruth, after they returned to the United States following a tour in Africa and the Middle East.

Graham gets a kiss from his wife, Ruth, after they returned to the United States following a tour in Africa and the Middle East.

Supporters greet Graham upon his arrival in New York in 1959. Graham and his wife were returning from a six-month speaking tour that included stops in Australia and the Soviet Union.

Supporters greet Graham upon his arrival in New York in 1959. Graham and his wife were returning from a six-month speaking tour that included stops in Australia and the Soviet Union.

US President Dwight D. Eisenhower visits with Graham at the White House in 1957.

US President Dwight D. Eisenhower visits with Graham at the White House in 1957.

Graham embraces his family upon his return from his "Crusade for Christ" tour in the 1950s. With him from left are his wife, Ruth, and his daughters Anne, Virginia and Ruth (Bunny).

Graham embraces his family upon his return from his "Crusade for Christ" tour in the 1950s. With him from left are his wife, Ruth, and his daughters Anne, Virginia and Ruth (Bunny).

Graham speaks to soccer fans in London during halftime of a match between Chelsea and Newcastle United.

Graham speaks to soccer fans in London during halftime of a match between Chelsea and Newcastle United.

Graham reads on an airplane during a "Pulpit in the Sky" trip in 1953.

Graham reads on an airplane during a "Pulpit in the Sky" trip in 1953.

Graham preaches in the early 1950s. He said he became "born again" after hearing an evangelist at a tent meeting in 1934.

Graham preaches in the early 1950s. He said he became "born again" after hearing an evangelist at a tent meeting in 1934.

A school portrait of Graham, age 17, in 1935. After high school, Graham moved from Charlotte, North Carolina, to Tennessee to enroll in the conservative Christian school Bob Jones College. He then transferred to the Florida Bible Institute. He was ordained a Southern Baptist minister in 1939 and quickly gained a reputation as an evangelical preacher.

A school portrait of Graham, age 17, in 1935. After high school, Graham moved from Charlotte, North Carolina, to Tennessee to enroll in the conservative Christian school Bob Jones College. He then transferred to the Florida Bible Institute. He was ordained a Southern Baptist minister in 1939 and quickly gained a reputation as an evangelical preacher.

Evangelist Billy Graham, who reached millions of people through his Christian rallies and developed a relationship with every US president since Harry Truman, died Wednesday, February 21, at the age of 99.

Evangelist Billy Graham, who reached millions of people through his Christian rallies and developed a relationship with every US president since Harry Truman, died Wednesday, February 21, at the age of 99.

Graham was tall and handsome, with a disarming aw-shucks demeanor and a Southern twang to his voice. But Graham's influence, historians say, was monumental. Some called him "America's pastor," others referred to him as the "Protestant pope."

Graham is reported to have persuaded more than 3 million people to commit their lives to Christianity and his preaching was heard in 185 of the world's 195 countries, according to the Billy Graham Evangelistic Association.

"He was probably the dominant religious leader of his era; no more than one or two popes, perhaps one or two other people, could come close to what he achieved," said William Martin, a former historian at Rice University and the author of "A Prophet with Honor: The Billy Graham Story."

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Condolences and funeral plans

A private family prayer service is set for Saturday. Public viewing and services will be held in the following days, culminating with a March 2 invitation-only service and burial in Charlotte at the Billy Graham Library alongside his wife, Ruth.

People across the world mourned Graham's death.

President Donald Trump said in a tweet that "the GREAT Billy Graham is dead. There was nobody like him! He will be missed by Christians and all religions. A very special man."

The GREAT Billy Graham is dead. There was nobody like him! He will be missed by Christians and all religions. A very special man. — Donald J. Trump (@realDonaldTrump) February 21, 2018

Vice President Mike Pence said in a statement that "Karen and I were saddened to learn of the passing of one of the greatest Americans of the 20th century, Reverend Billy Graham."

"We send our deepest condolences to the Graham family. Billy Graham's ministry for the gospel of Jesus Christ and his matchless voice changed the lives of millions. We mourn his passing but I know with absolute certainty that today he heard those words, 'Well done, good and faithful servant.' Thank you Billy Graham. God bless you."

Former President Jimmy Carter said in a statement that he and his wife Rosalynn "are deeply saddened" at the news of Graham's death and that he was "pleased to count Reverend Graham" as a friend and adviser.

"Tirelessly spreading a message of fellowship and hope, he shaped the spiritual lives of tens of millions of people worldwide," Carter said in a statement. "Broad-minded, forgiving, and humble in his treatment of others, he exemplified the life of Jesus Christ by constantly reaching out for opportunities to serve. He had an enormous influence on my own spiritual life."

Former President George H.W. Bush called Graham "America's pastor" and said he was a mentor to several of his children, including former President George W. Bush.

"His faith in Christ and his totally honest evangelical spirit inspired people across the country and around the world. I think Billy touched the hearts of not only Christians, but people of all faiths, because he was such a good man," the elder Bush said in a statement

Bush said he was "privileged" to count Graham as a "personal friend."

"He would come to Maine to visit with Barbara and me, and he was a great sport. He loved going really fast in my boat. I guess you could say we had that in common. Then we would come home and talk about life."

Russell Moore, the president of the Ethics & Religious Liberty Commission of the Southern Baptist Convention, said on Twitter that Graham was "the most important evangelist since the Apostle Paul."

"He preached Christ, not himself, not politics, not prosperity," Moore said, adding that Graham also "carried unimpeachable personal integrity."

RIP Billy Graham, a good and faithful servant. He fought the good fight, finished the race, and kept the faith. — Ron DeSantis (@RepDeSantis) February 21, 2018

"RIP Billy Graham, a good and faithful servant. He fought the good fight, finished the race, and kept the faith," US Rep. Ron DeSantis, who represents Florida's 6th District, said on Twitter.

Televangelist Joel Osteen told CNN that Graham was his hero, and said the best way to honor him is for Christians to continue what he started.

"Preaching good news and letting people know about Christ and the love and respect that we can show one another. I think it's to continue on in that passion. He took great steps of faith. He paved the way for young ministers like myself."

The creation of a ministry

Graham built his ministry by bringing the gospel message of tent-revival preachers into the modern media age, using any tool at his disposal -- from telegrams to telephones to satellites and the Internet -- to "win souls for Christ."

In doing so, Graham formed a bridge between the itinerant preachers like Dwight Moody and Billy Sunday who once crisscrossed the country in search of lost souls and contemporary Christian pastors like Joel Osteen, Rick Warren and T.D. Jakes.

"He saw himself as using new media to deliver a very old message," said Randall Balmer, an expert on American religious history at Dartmouth College.

That message, as Graham said during thousands of altar calls, was that salvation is offered to one and all, black and white, rich and poor, men and women, sinners and saints, so long as they believed in Jesus.

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Crusades and cathedrals

Avoiding the types of public scandals that befell other prominent preachers was key to Graham's long-running success, said Martin.

In 1948, at the beginning of his rise to fame, Graham and his tight circle of traveling evangelists gathered in California and catalogued the sins that had destroyed the careers of other Christian preachers. Money, sexual temptation and hubris topped the list.

Their pledge to avoid all three came to be known as the "Modesto Manifesto" and was later adopted by other ministers looking to avoid public disgrace.

In return for his scandal-free life, Americans regularly put Graham at the top of "most-admired" people polls. In 2013, he tied for fourth among most-admired men with former President Bill Clinton. It was his record-setting 57th appearance in the top 10, according to Gallup.

"In my favorite poll, I believe it was the Ladies' Home Journal, he was chosen second only to God in achievements in religion," Martin said.

Missionary work

Graham began his missionary work in 1944 by speaking at rallies for the Youth for Christ Campus Life ministry.

Five years later, he branched out on his own, holding a tent crusade in downtown Los Angeles. Originally scheduled for three weeks, the crusade drew such large crowds that it was extended to seven; a radio disc jockey, a small-time mobster and an Olympic athlete were among those who accepted his altar call under the "Canvas Cathedral."

The next year, Graham founded the Billy Graham Evangelistic Association.

The crusades, which soon became the signature feature of his global ministry, frequently blended well-known hymns, preaching and patriotic displays.

"His sermons contained just the right mix of patriotism and reproof," said Molly Worthen, a religious historian at the University of North Carolina. "He urged Americans to stand strong against 'godless communism' but also criticized American hubris."

Graham told an audience in Charlotte in 1958 that, "We have an idea that we Americans are God's chosen people, that God loves us more than any other people, and that we are God's blessed. I tell you that God doesn't love us any more than he does the Russians."

Graham's crusades mobilized hundreds of volunteers not just from his own evangelical movement but also from liberal Protestant congregations and Catholic parishes.

His inclusive message -- he said that theological differences were less important than Christian comity -- angered some fundamentalists, who fulminated when he shared the stage with Catholic or liberal Protestant ministers.

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The traveling messenger

Graham was seldom still, holding crusades in more than 80 countries, according to Martin, often for weeks and months at a time. He missed the birth of his first daughter, Virginia, because he was away on a preaching trip, the biographer said. At other times, he failed to recognize his own children because he had been away from home so long.

Graham led a 12-week crusade in London in 1954 and a 16-week revival in New York in 1957, which drew tens of thousands to Madison Square Garden.

At the time, Graham praised New York's religious diversity, saying, "Almost every religion you can think of in the whole world is represented." His "last crusade" in June 2005 in Queens, New York, drew a total of 230,000 people.

In addition to his traveling crusades, Graham hosted a weekly Sunday radio program called "The Hour of Decision" and wrote an advice column, "My Answer," that was distributed by Tribune Media Services. In 1956, he founded the magazine Christianity Today, a leading publication among evangelicals.

Presidents and critics

William Franklin Graham Jr. was born November 7, 1918, and raised on a dairy farm near Charlotte, North Carolina. He said he made a personal commitment to God in 1934 after hearing an evangelist preach in the Southern city.

He graduated in 1940 from the Florida Bible Institute, now Trinity College, with a bachelor's degree in theology. Graham was ordained that year by a Southern Baptist church in Florida. A few years later, he took over a Chicago radio program, "Songs in the Night."

While in Florida, Graham met relatives of V. Raymond Edman, president of Wheaton College in Wheaton, Illinois. After they told Edman how impressed they were with Graham's preaching ability, Edman arranged for him to attend Wheaton.

Graham graduated in 1943 with a bachelor's degree in anthropology.

At Wheaton, he met fellow student Ruth Bell, his future wife. She was the daughter of the Southern Presbyterian missionary and surgeon L. Nelson Bell, and Ruth had spent her childhood in China and Korea.

The couple married in 1943 and moved to Montreat, North Carolina, two years later. They had five children: Virginia Leftwich, Anne Morrow, Ruth Bell, William Franklin III and Nelson Edman.

Graham was said to have enjoyed the recognition that came with providing counsel to several U.S. presidents, and he also became a de facto chaplain to Washington's elite.

Graham urged Dwight Eisenhower to run for president in 1952 and served as an unofficial adviser to the former general after he was elected. He also became close friends with President Lyndon Johnson and preached at the former president's funeral. President George W. Bush credits Graham with helping him change from a lukewarm Christian with a fondness for beer to a serious and committed evangelical.

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Critics accused Graham of becoming too involved with politics.

His association with President Richard Nixon led to embarrassment in March 2002, when tapes of private conversations between Nixon and Graham revealed the evangelist joining the president in making anti-Semitic remarks. Graham apologized.

"After Watergate, Graham understood that he had been used to support Nixon and his policies when the White House was more interested in his support than his love," said Martin, the biographer.

Some critics also charge that Graham was not active enough during the civil rights movement.

But during at least two crusades in the early 1950s in Tennessee and Mississippi, Graham literally removed the racial barrier -- taking down the ropes that separated blacks and whites -- according to Martin and Cliff Barrows, Graham's longtime music and program director for the Evangelistic Association.

"Billy himself went and took the rope down and said, 'We don't have segregated meetings, whatever their reason for segregating them. They can sit wherever they want to.' And he took a stand for his belief that every man is equal before Christ and the gospel was for everyone."

At his Madison Square Garden crusade, Graham asked the Rev. Martin Luther King Jr. to deliver a prayer. Although Graham preached that racial segregation was unbiblical, he was criticized by some civil rights leaders for not being more involved in the movement.

A week after the deadly bombing of a church in Birmingham, Alabama, in 1963, Graham told fellow evangelicals: "We should have been leading the way to racial justice but we failed. Let's confess it, let's admit it, and let's do something about it."

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Among the honors bestowed on Graham were the Presidential Medal of Freedom, the nation's highest civilian award, in 1983; the Congressional Gold Medal in 1996; and an honorary knighthood from Britain for his contribution to civic and religious life.

Former Presidents Clinton, George H.W. Bush and Carter were on hand for the dedication of the Billy Graham Library in Charlotte in June 2007.

In addition, the Billy Graham Center on the campus of Wheaton College has an archive, museum and library dedicated to the study of evangelism, as well as an Institute of Evangelism and other efforts aimed at promoting evangelistic work throughout the world.

The love of his life

In 2005, Graham opened up to CNN about his wife, Ruth. "I don't think I could have ever married anybody that would have been more helpful to my work and ministry than she has been," he told Larry King.

She died in 2007 at the couple's home in Montreat.

"Ruth was my life partner, and we were called by God as a team," Graham said in her obituary. "No one else could have borne the load that she carried."

Ruth Graham was buried at the foot of a cross-shaped walkway in the Prayer Garden on the grounds of the Billy Graham Library. The couple had agreed that they would be buried side by side.

Asked what he'd like people to say about him when he died, Graham said, "I want to hear one person say something nice about me and that's the Lord, when I face him. I want him to say to me, 'Well done, thou good and faithful servant.'"