Arlene Foster has been urged to ensure a restored assembly allows a free vote on marriage equality and to help combat wider discrimination against the LGBT community.
The call came from Alliance MLA Paula Bradshaw ahead of the DUP leader's attendance at today's PinkNews summer reception in Parliament Buildings.
Mrs Foster is scheduled to speak at the event, which is one of a number of outreach engagements she has undertaken in recent weeks.
In the past the DUP has used a petition of concern to veto the outcome of assembly votes on same sex marriage.
Ms Bradshaw, who is the main sponsor of today's Stormont reception, said its aim was to celebrate the contribution of LGBT people to society.
She welcomed the former first minister's decision to attend.
"Her decision to be there means just like the rainbow flag, there will be a full spectrum of political representation at the reception – I am sure it can be the beginning of a positive engagement," the South Belfast representative said.
"But we all now need to take responsibility for building on the positive sense of togetherness this has created, to work towards better supporting LGBT people in the community."
The Alliance MLA said Mrs Foster could help ensure a restored assembly would have a free vote on same sex marriage, while helping eliminate discrimination against LGBT people.
Ahead of today's event, PinkNews published a survey that found that an overwhelming majority of voters in Britain support same-sex marriage in Northern Ireland. The survey of nearly 1700 adults found 80 per cent of people in Britain back equal marriage compared to 66 per cent in the north.
PinkNews editor in chief Benjamin Cohen said: "It is exciting that across the UK, there is clear support for same-sex marriage being introduced in Northern Ireland, the last part of the country where gay people are banned from marrying.
"This shows how much attitudes have changed since the first same-sex weddings in England, Wales and Scotland in 2014."
Meanwhile, same sex marriage campaigners have welcomed a Supreme Court judgment giving same sex couples the right to have a civil partnership instead of marriage.
Patrick Corrigan of the Love Equality campaign for marriage equality in the north described yesterday's ruling as "very significant".
"There is an exact parallel with the provision of access to marriage for opposite-sex couples, but not same-sex couples in Northern Ireland – this is clearly discriminatory," he said.
"The government should now move quickly – not only to equalise the law on civil partnerships, but also to end discrimination against LGBT+ couples in Northern Ireland by amending equal marriage legislation."
