The evangelist quietly headed a group that sowed doubts about a Roman Catholic's ability to govern the country without being influenced by the Vatican.

As the administration of Dwight D. Eisenhower neared its end in 1960, American citizens faced the question of whether incumbent Vice President Richard Nixon or Massachusetts Senator John F. Kennedy was better equipped to lead the country at a time of a changing racial landscape at home and a looming communist threat abroad.

But there was another divisive factor at play, the so-called "religious issue," which centered on Kennedy's bid to become the first Roman Catholic president. While freedom of worship ostensibly remained a core value of the republic (Nixon himself was in the minority as a self-professed Quaker), it became an open question as to whether a Roman Catholic president could govern without being swayed by the Vatican.

Nixon advised Graham to keep his political thoughts to himself

Some prominent Protestant leaders, like Norman Vincent Peale, author of the 1952 best-selling self-help guide The Power of Positive Thinking, maintained that it would be impossible for JFK to separate himself from the influence of the Catholic Church.

Others, like the world-famous Baptist evangelist Billy Graham, were more apprehensive about appearing to favor either candidate. According to his 1994 book, Beyond Peace, Nixon himself suggested Graham should stay out of the fray. "Government cannot reach into people's hearts. Religion can," wrote the controversial politician. "I told [Graham] he would undermine his own ability to change people spiritually if he engaged in activities designed to change governments politically."

Still, Graham had his biases: He was personally much closer to the Republican candidate, having visited him several times over the past decade to discuss theology and politics. Additionally, Graham believed Nixon's eight years as vice president left him better suited to take over the top job in the White House.

So, while a public stance didn't serve his purpose well, there was little stopping his behind-the-scenes efforts to tip the scales toward his preferred candidate.

Billy Graham and John F. Kennedy at the National Prayer Breakfast in Washington D.C. in February 1961.

Billy Graham and President John F. Kennedy at the National Prayer Breakfast in Washington D.C. in February 1961.

Graham convened a secret meeting of influential church leaders

As noted in Carol George's 1992 biography of Peale, God's Salesman, Peale sent Nixon a letter while vacationing in Europe in August 1960, divulging that "Recently I spent an hour with Billy Graham, who feels as I do, that we must do all within our power to help you."

The book also told of a secret meeting of influential allies around that time, as revealed through a letter from Peale's wife, Ruth, to a friend. "Norman had a conference yesterday at Montreux, Switzerland, with Billy Graham and about 25 church leaders from the United States," she wrote. "They were unanimous in feeling that the Protestants in America must be aroused in some way, or the solid block Catholic voting, plus money, will take this election."

A second, more public meeting involving many of the same participants was scheduled for September 7 in Washington, D.C. With Graham still out of the country – and pleading ignorance to events that unfolded without him – Peale became the face of the gathering and was promptly blasted for holding a conference on the Catholic Church's shortcomings without input from liberal theologians or representatives of other faiths. The outcry was such that many newspapers dropped Peale's syndicated column, and he even offered to resign his pastorship at New York City's Marble Collegiate Church.

READ MORE: 12 Notable Members of the Kennedy Family

Kennedy delivered a well-regarded speech to answer his critics

The public outcry provided an opening for Kennedy to address the subject with sympathies on his side. In mid-September, he delivered a convincing speech to the Greater Houston Ministerial Association:

"I am not the Catholic candidate for president. I am the Democratic Party's candidate for president, who happens also to be a Catholic," he said. "I do not speak for my church on public matters, and the church does not speak for me. ... But if the time should ever come – and I do not concede any conflict to be even remotely possible – when my office would require me to either violate my conscience or violate the national interest, then I would resign the office; and I hope any conscientious public servant would do the same."

Late in the campaign, Graham finally came forward with his support of Nixon, though his endorsement wasn't enough to overcome what became a slim popular vote and comfortable electoral college vote win for Kennedy.

Billy Graham shakes hands with President John F. Kennedy during an unannounced visit to the White House in December 1961

Billy Graham shakes hands with President John F. Kennedy during an unannounced visit to the White House in December 1961.

Kennedy had Graham answer the religious issue one last time before JFK's inauguration

Whether or not JFK got wind of Graham's covert maneuverings, he forged an amicable relationship with the evangelist and even exacted a bit of revenge, as recalled in Graham's 1997 memoir, Just as I Am.

Ten days before the inauguration, Graham was invited to meet with Kennedy in Palm Beach, Florida. After a round of golf, the president-elect said he needed to address the press corps waiting for him at a hotel, and asked the reverend to tag along.

Graham acquiesced, and he was sitting with the media horde when Kennedy announced that his not-so-anonymous guest would be taking questions. Surprised, Graham nevertheless took the opportunity to clear up any perceptions about his preferences and attempt to put the religious issue to rest.

"I don't think that Mr. Kennedy's being a Catholic should be held against him by any Protestant," he said. "They should judge him on his ability and his character. We should trust and support our new president."