Legislation to allow for a referendum on same sex marriage has been passed in the Seanad with a standing ovation by many of those supporting the Bill.

The Thirty-Fourth Amendment of the Constitution (Marriage Equality Bill) was accepted by 29 votes to three in the Upper House after a week of sometimes heated debate.

The legislation now goes to the President for signature, having been passed by the Dáil without a vote.

The Bill was passed as an opinion poll in The Irish Times showed a 6 per cent drop in support for the introduction of same sex marriage since December when the last poll was conducted. The referendum takes place on Friday, May 22nd.

Support stands at 74 per cent compared to 80 per cent in the last poll. Support for a No vote has risen 6 per cent to 26 per cent, when undecided voters are accounted for.

A number of amendments from Independent Ronán Mullen were rejected including that marriage equality should not have “unintended consequences” affecting what he called freedom of conscience issues.

Mr Mullen said that “as a general principle, it should always be immoral and unlawful to discriminate against a person on grounds of his or her sexual orientation.

“However, refusing to provide a service in circumstances which one perceives to link one with something with which one conscientiously disagrees is not the same thing.”

He highlighted the case of a bakery in Belfast which refused to provide a cake for a civil partnership and was being prosecuted by what he called the “equality people” in the North.

He said people sometimes found themselves unable to act in accordance with what they were asked to do because of a sincerely held view which might be political or religious.

“Tolerance is about facilitating the point of view of the person whose view you actually despise,” he said.

But Independent Katherine Zappone said the fundamental issue at stake here was “about the protection of a minority’s right to marry by opening a civil institution, to be protected and be able to become a constitutional family”.

There was equality legislation in place which was not changing and dealt with discrimination in the provision of goods and services and “whether or not they are discriminating against people in this case because of their sexual identity”.

In an emotional address to the Upper House Ms Zappone pointed out that when attempts were made to give additional layers of protection to the religious ethos of institutions, there were “extraordinarily negative consequences for teachers, nurses and other civil servants to be fearful of revealing their identity and who they are in partnership with”.

She said: “ What will change is that a minority who is oppressed and who is unequal in terms of our Constitution because they do not have access - I am banned from the civil institution of marriage because of my sexual identity - that they will become free, become equal to heterosexual couples who have the right to access to marry.”

Minister for Justice Frances Fitzgerald said Mr Mullen’s amendment would “have the effect of limiting the constitutional effect” of the referendum.

She was also concerned that the amendments would result in “a hierarchy of rights whereby one person’s rights to freedom of religion would always be superior to another person’s rights to equality of participation in our society”.

Ms Fitzgerald said the core proposal in the referendum was about making the right to marry available to same-sex couples that is available to opposite-sex couples.

“If the people approve this proposal in the referendum, this right will also need to be protected.”

She also expressed concern about Mr Mullen’s “explicit reference to Article 42, which addresses education and the rights of children”.

The Minister stressed the referendum “is not about children or education. It is about marriage” and it was misleading to seek to add irrelevant issues into the equation.