Washington was now buzzing with as many rumours as had swept London during the height of the scandal, so what happened next was not entirely a surprise. The White House became involved. The most likely explanation for President Kennedy’s sudden interest in the affair is that his brother, Attorney-General Robert Kennedy, told him of the long report from Hoover.
There were then both political and personal reasons for the President’s interest. One was that the scandal could provide Kennedy’s opponents in Congress with ammunition to attack his plans for a multi-nation NATO nuclear force. If Britain was so leaky, why should the US share it’s defence secrets? Another was a call in the Washington News for Kennedy to cancel his scheduled visit to London because it would provide moral support for the foundering Government of Harold Macmillan. ‘We can think of no better time for an American President to stay as far as possible away from England.’
And a third reason, a personal one, was that given Hoover’s animosity for the Kennedy family, the President became concerned that Hoover would somehow use the scandal against him….The only feasible reason for this widespread fascination is that all these people feared that the President of the United States was about to be dragged into the scandal, not on a political level, but on a sexual one…..The reason was that Robert Kennedy was worried that Christine or Mandy, or even both girls, might have slept with the President during their recent visit to the United States and he needed to know for certain so that he could protect the President from the scandal that would follow if the girls blabbed. It would have been simpler for Robert Kennedy to ask his brother if he had slept with either of the girls. But, as we now know, John F. Kennedy’s sexual appetite was so prodigious and so indiscriminate that he would not have been able to remember.