One was on his way to the White House. The other was the king of Hollywood. It was a match made in heaven.

In early February 1960, Massachusetts Senator and presidential candidate John F. Kennedy checked in to the Sands Hotel and Casino in Las Vegas to catch one of the legendary performances of Frank Sinatra and the Rat Pack. Amid the show, Sinatra stepped forward to point out Kennedy, seated next to the stage, and introduced him as the "next president of the United States."

It marked a public intersection of politics and entertainment that was rare for the time and highlighted a bond between the two luminaries that reached its peak over a wild campaign season.

The crooner and the candidate had already been friends for a few years. It's unclear when they first met, but they shared a connection through the marriage of JFK's sister Pat to actor and Rat Packer Peter Lawford, and by the end of the 1950s they were well acquainted.

Frank Sinatra and John F. Kennedy

Frank Sinatra and John F. Kennedy at Kennedy's inaugural ball at the Mayflower Hotel in Washington D.C, in January 1961

Sinatra used his star power to help JFK win votes

The Sinatra-Kennedy pairing was, in part, an alliance of shared interests. Given the former's influence as a top-selling recording artist and A-list movie star, the campaign figured he was the perfect person to recruit fellow high-profile entertainers to spread the word and open their pocketbooks in support of the rising politician. Furthermore, Kennedy patriarch, Joseph, reportedly wanted Sinatra to use his organized crime ties to influence the union vote, dangling a potential administration position as motivation.

But there was also very much a mutual admiration between the two. Sinatra represented the glamour of Hollywood, and with the rest of the Rat Pack – primarily consisting of singer-actors Dean Martin and Sammy Davis Jr., comedian Joey Bishop and Lawford – they projected an image of urban sophisticates who coasted on their talents and were too cool to follow rules.

Kennedy, on the other hand, represented big-time power, a connection to congressional corridors and the kingmakers who helped determine who was running the country. In a grass-is-greener sense, each found the other to be living an enviable life.

They both had an appetite for partying and women

They met in the middle over a shared taste for nightlife and women, and Sinatra was all too happy to oblige his friend's desires. The Vegas after-parties were stocked with plenty of booze and female fans, as were the festivities held at Lawford's Santa Monica home when the campaign swung through California. It was Sinatra who introduced Kennedy to Marilyn Monroe and a lesser-known mistress named Judith Campbell, who later complicated things with her own connections to the mob.

Beyond the parties, Sinatra engaged in major leg work for the candidate: He organized donor dinners, appeared in radio ads and lent his private jet to Kennedy operatives. At concerts, he performed a reworked version of his hit "High Hopes," which served as the theme song of the campaign.

Kennedy emerged triumphant, of course, producing Ol' Blue Eyes' final contribution to the cause: A pre-inauguration gala at the National Guard Armory in Washington, D.C. headlined by showbiz all-stars like Gene Kelly, Nat King Cole, Milton Berle, and Ella Fitzgerald. Sinatra took turns performing and watching from the Kennedy box, and afterward, the president-elect took the stage to say he how indebted he was to Sinatra's efforts.

Frank Sinatra escorting Jacqueline Kennedy to her box at a gala, held at the National Guard Armory in Washington DC, the night before the inauguration of President John F. Kennedy

Frank Sinatra escorting Jackie Kennedy to her box at a gala, held at the National Guard Armory in Washington DC, the night before the inauguration of President John F. Kennedy in January 1961

After JFK won, their friendship began to crumble and Sinatra was banned from the White House

But there were already cracks in the relationship, and they became more apparent once Kennedy officially took office. For one thing, First Lady Jackie Kennedy reportedly despised the singer and did not want him anywhere near the White House. (Years later after JFK's death, the pair would go on a dinner date.) Additionally, Sinatra flaunted his friendships with crime bosses, an association at odds with the anti-mob mentality of Attorney General Robert Kennedy.

Things came to a head when FBI chief J. Edgar Hoover approached the administration with potentially damaging information in March 1962, though stories differ as to what he revealed. 

One account is that Hoover shared recordings of Judith Campbell's calls to the White House as well as those to Chicago Outfit boss Sam Giancana, tying the President to one of the notorious gangsters of the era.

Another is that wiretaps revealed Sinatra to be discussing his affair with JFK's sister Pat  – an affair undertaken with the purpose of influencing the administration into easing off the mob.

Whatever was learned, Sinatra was immediately out of the Kennedy circle. Lawford was told to break the news to the volatile entertainer, and as expected, it did not go over well. Sinatra had constructed a helipad and an elaborate communications system at his Palm Springs home in expectation of a presidential visit, and he proceeded to smash everything in sight. He also took out his anger on the messenger, cutting Lawford out of future Rat Pack projects.

Thus ended the short but emotionally charged friendship between two of the most prominent figures of 20th century American culture. And, as is the case with most relationships filled with good times, platonic or otherwise, the memories lingered: When JFK was assassinated in November 1963, according to Sinatra's daughter Nancy, her dad cried for days.

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