Ireland’s only out lesbian senator has challenged an opponent to a public debate, ahead of the country’s referendum on same-sex marriage.

The Republic of Ireland is set to vote on proposals to introduce civil same-sex marriage on May 22, just over two months away.

Independent Senator Katherine Zappone – the only openly lesbian Senator in the country – has challenged Senator Rónán Mullen to a debate on the issue.

Rónán Mullen – a consistent opponent of equality – recently accused the country’s media of a “groupthink” on the issue.

Responding to his comments, Senator Zappone wrote to the Irish Times: “I am surprised by the claims of Senator Ronan Mullen (…) that members of the media are participating in groupthink with regard to the forthcoming referendum.

“Mr Mullen also says that he looks forward to a more balanced debate as the referendum approaches, and that it has been ‘all emotionalism’ up to now.

“In my view this is a debate that calls upon all dimensions of human intelligence – emotional, spiritual and rational.

“I think that this is the debate that we are having now in the public domain and at dinner tables up and down the country.

“As for the future, would Mr Mullen like to meet me on the public debate trail?

“For that matter, I would be keen also to participate in a respectful and public debate with Archbishop Diarmuid Martin as well.”