One of four remaining Democratic Senators not to have backed marriage equality said in an interview on Friday that he was “undecided” on the issue, and added he had “never really thought” about whether being gay is a choice.

Mark Pryor, Democratic Senator for Arkansas, was asked about his position on marriage equality in an interview with KFSM 5 News.

He said: “I would put me down in the undecided category.”

“I did talk with some friends of mine in the gay and lesbian community over the last week or so,” he added. “We talked about this issue. We also talked about a question I received in the office not too long ago where they asked whether being gay was a choice or whether you were born that way. I told them, I said, ‘Honestly I’ve never really thought a lot about that.’ Maybe a lot of people think about that. I haven’t spent a lot of time thinking about that. But one of the things I hear from them is they feel very strongly that it’s not a choice for them, and I respect that. I’m not going to dispute that. I appreciate that, and I appreciate their honesty.

“For a lot of these people they just really open their heart to me and talked about some of the struggles they’ve had over the years with their sexual orientation. I respect that and appreciate their patience, and I appreciate their honesty.”

Mr Pryor is one of just four Democratic Senators who have not backed marriage equality, out of a total of 53. In contrast, only two out of 45 Republican Senators support it.

Yesterday Democratic Senators Heidi Heitkamp and Joe Donnelly each announced their support for equal marriage via Facebook.

Democratic Senator Timothy Kaine also shifted his position on Tuesday to support equal marriage.

He followed Democratic Senators Mark Begich and Mark Warner, who both came out in support of same-sex marriage before the Supreme Court’s hearings on the subject, following the precedent set by Claire McCaskill. Senator McCaskill announced her support via a Tumblr post.

Earlier this week Republican Senator Mark Kirk declared his support for equal marriage, saying: “Life comes down to who you love and who loves you back – government has no place in the middle.”

Republican Senator Rob Portman announced that he  endorsed same-sex marriage on 15 March.

The announcement was particularly surprising as Mr Portman had been one of the original sponsors of DOMA. He said the coming out of his gay son had prompted him to rethink his views.