Former Massachusetts Congressman Barney Frank says he knows of 7 closeted members of Congress.

The 73-year-old Frank has the distinction of being the first openly gay member of Congress and the first to enter a marriage with a member of the same sex.

Frank spoke over the weekend at the Commonwealth Club of California in San Francisco. The organization is the oldest and largest non-partisan public affairs forum in the United States.

“I'm glad to see so many of you who apparently have attention spans that exceed a tweet,” Frank is quoted as saying by San Francisco gay weekly The Bay Area Reporter.

He praised former President Bill Clinton as “a hero of gay rights.” Clinton, Frank said, was strong-armed by anti-gay Republicans into signing “Don't Ask, Don't Tell,” the now-ended law which prohibited openly gay military service.

“[I]t was the best Clinton could do” at the time, he said.

Frank also told the audience, estimated at 500, that “being gay in Washington D.C., is not easy,” adding that he knew of three senators and four House members who are closeted, but he refused to mention names.