In an interview with, former congressman Barney Frank said Republicans are “getting worse” at LGBT rights.

The 74-year-old openly gay Frank is currently pitching his new memoir, Frank: A Life in Politics from the Great Society to Same-Sex Marriage.

Earlier this month, Ben Carson, a possible GOP presidential candidate, made headlines when he said that prison can make people gay.

“Absolutely,” Carson answered when asked if being gay is a choice. “Because a lot of people go into prison straight and when they come out they're gay.”

(Related: Ben Carson opposed to marriage equality because some inmates turn gay in prison.)

Later in the day, Carson apologized for the remark and vowed he would no longer talk about gay rights.

“I did tell MSNBC that I did want to know when he decided to be straight,” Frank told Salon.

“When do you think we'll finally reach a point where even Republican primary voters won't accept that kind of talk about LGBT people?”

“The most disturbing thing about that was that it did not seem to trouble Republican primary voters,” Frank answered. “[T]he answer is yeah, but it may be another 20 years.”

“When I started in politics, there was no difference between the parties; both parties were totally homophobic, including John Kennedy and Lyndon Johnson. Things began to change after Stonewall, so in ’76 there was very little difference between Gerry Ford and Jimmy Carter on this. They moved both parties with the country, and then Reagan comes in and the right wing takes over. So you’ve had three trend lines since the 1970s: the country is getting better at an even faster pace than I thought, the Democrats are getting better at an even faster pace than the country, and the Republicans are getting worse.”

“I think it’s going to be generational. I think you’re not going to see Republican presidential candidates doing that as much as they have in the past, and I include Romney in this. When we got marriage equality in Massachusetts, Romney – who was then the governor – decided he was going to make a name for himself as a Republican by leading the attack on us. I’m afraid it’s going to take another 20 years because primary voters tend to be older because it’s self-selecting. The Republican primary has now become extremely significant, and one of the things I hope will happen is that mainstream conservative voters will reassert themselves,” he added.