Campaigners are calling for a firm commitment to deliver same-sex marriage before the next Northern Ireland Executive is formed.
A group made up of members of Amnesty International, the Irish Congress of Trade Union, the Rainbow Project and Cara Friend say a change in the law would be a 'litmus test' for any new Executive.
The Assembly backed equal marriage in 2015 but a DUP petition of concern blocked the motion.
In the new Assembly, the DUP do not have enough seats to mount a veto - but other unionists could join a pact to block the measure.
Declan Meehan from the Love Equality coalition said: "All of the people of Northern Ireland must be served by the incoming government - that includes the LGBT community.
"Before any new Executive is formed, there must be a firm commitment to deliver equal marriage legislation.
"Without that, we know it will be another five years of LGBT people being treated as second-class citizens of Northern Ireland."