Former New York City Mayor Ed Koch, who died on Friday at the age of 88, was known for his outspokenness. Yet, there was one area involving his personal life that Koch never discussed: his sexuality.

Koch’s unwillingness to speak about this aspect of his personal life led to rumors that the three-term mayor was gay. Koch never married.

When then-congressman Koch ran against New York Secretary of State Mario Cuomo for mayor, anonymous literature flooded the streets of the city, urging New Yorkers to “Vote for Cuomo, not the Homo.” Cuomo denied being behind the offensive fliers.

In an effort to defuse the gay rumors, Koch had Bess Myerson, a former Miss America, by his side during campaign events in 1977. Later, Koch said that he and Myerson were not romantically involved, Reuters reported, and he denied being gay.

"No, I am not a homosexual. If I were a homosexual, I would hope I would have the courage to say so,” he said at the time, in a New York Daily News article. “What's cruel is that you are forcing me to say I am not a homosexual. This means you are putting homosexuals down. I don't want to do that."

When Koch was asked years later about his sexuality, he would not confirm whether he was straight or gay.

“It’s none of your f------ business,” Koch said, in a documentary about his three terms as mayor. The film opens in theaters on Friday.

“My answer to questions on this subject is simply, ‘F—- off. There have to be some private matters left,” he once said.

Koch served as mayor from 1978 to 1989, and he acknowledged that some New Yorkers had suspicions about his sexuality.

In an article he did 15 years ago for New York magazine, Koch, then 73, joked that he relished the idea other people would be curious about an old man's sexual orientation.

“Listen, there’s no question that some New Yorkers think I’m gay, and voted for me nevertheless. The vast majority don’t care, and others don’t think I am,” Koch said in the article. “And I don’t give a s--- either way! What do I care? I’m 73 years old. I find it fascinating that people are interested in my sex life at age 73. It’s rather complimentary!”

Koch was among the politicians featured in “Outrage,” a 2009 documentary, about closeted gay elected officials.

In the film, Koch was said to have had a boyfriend, Richard Nathan, who left the city when Koch was first elected mayor; however, Koch denied having a romantic relationship with Nathan, who later died of AIDS, the New York Daily News said on Friday.