US History Trivia: Which of these President's was rumored to have had a homosexual relationship with another man?

Our US History games have been flying like hot-cakes lately...so let's keep going with that, shall we?

Sex scandals and President's seem to go hand-in-hand (though our last two Presidents, W and Obama, haven't even had a hint of a sex scandal).  If power is truly an aphrodisiac, then that makes sense; power can make the President the most attractive man on the planet!

However, only once in history have substantial rumors circulated that a particular President was, in fact, having a sexual relationship with another man.   So, off of Pocket Trivia: US History - Which of these President's was rumored to have had a homosexual relationship with another man?  Was it Millard Fillmore, Grover Cleveland, Woodrow Wilson or James Buchanan?