Massachusetts Rep. Barney Frank on Thursday refused to comment on the rumor that South Carolina Senator Lindsey Graham is gay.

During an appearance on C-SPAN's American Journal, a caller named Frank from Largo, Florida told Frank that he was concerned that closeted lawmakers could be blackmailed during critical budget talks.

“In terms of the budget, I feel that many members of Congress may be compromised or blackmailable because they are in the closet about their sexual orientation, like Senator Lindsey Graham. And I was wondering, how many people in Congress do you think are compromised in that nature?”

“I have no comment to make about any individual, and no knowledge about any individual,” Frank responded. “There are some members of Congress who have not made that public.”

“Increasingly, if you're a Democrat … you pay no penalty for being honest about your sexuality,” Frank said.

“The problem is on the Republican side. Because the Republican Party has become increasingly opposed to the notion of legal equality for people who are gay, lesbian, bisexual or transgender. … The Republican Party will tolerate them as long as they don't appear to be happy about it.”

“Essentially their attitude is, 'OK, we understand that you can't help it but please … hide it,'” he added.

(Related: Senator Lindsey Graham, 'I Ain't Gay')