The leader of the SDLP is to address the Ulster Unionist Party conference in a bid to demonstrate the extent of cooperation between Stormont's two official opposition parties.
Colum Eastwood said his speech at Saturday's event in Belfast would prove that there was significant common ground between the parties, despite their many policy differences.
Former SDLP leader Margaret Ritchie addressed the UUP conference nine years ago. UUP leader Mike Nesbitt said the event would offer a tangible sign of cooperation. Both parties declined a position in the DUP/Sinn Fein led executive in the wake of May's Assembly election, instead choosing to take up the newly created option of forming an official opposition.
Mr Eastwood said: "This is a demonstration of what genuine cooperation looks like.
"Two leaders of two parties with different views coming together not in our own narrow self-interest, but in the interests of people across this region who deserve better from government.
"It's the principle of partnership, ingrained in our institutions by the SDLP and UUP and degraded by the current government, that brings us together on issues of common cause where we can make a positive difference to the lives of the people we represent.
"That commitment to cooperation does not mean absolute unanimity or uniformity - and nor should it. But it is a position of strength and it's the kind of cooperation that people want to see in our politics on issues like housing, homelessness and our health services.
"People across the North realise that Irish Nationalism and Unionism can never hope to seamlessly fit.
"However, our difference does not diminish our ability to pursue the commonality of our immediate cause. Both the SDLP and the Ulster Unionists share the common ground of wanting to make Northern Ireland work. That's a healthy common ground to hold for today and tomorrow.
"The constitutional change of the future will be the product of persuasion.
UUP leader Mike Nesbitt said: "Behind the scenes, there is a lot of joined up work going on between the SDLP and ourselves, but this is largely unseen and Colum and I are conscious that people want to see tangible signs of cooperation.
"Margaret Ritchie addressed our annual conference in 2007, while she was Social Development Minister, so this will be the first time we have welcomed a serving leader of the SDLP to our annual showcase. It's something the two parties of the executive are unlikely to match in the foreseeable future.
"We will not agree on everything, but rather than dwell on what divides us, I am focused on the common ground, and importantly, the fact that Colum and I both want Northern Ireland to work, which opens huge possibilities for cooperating on the bread and butter issues of the economy, education, housing and the health of all our people."