The UUP and DUP have jointly decided to seek an agreed unionist candidate to contest the forthcoming Mid Ulster by-election. The Mid Ulster branch of the UUP recently agreed to the idea at its AGM.
Party leader Mike Nesbitt, who was at the meeting, said: "We agreed that, whatever happens, there will be a candidate with Ulster Unionist values standing in the by-election, but it may not be a party member."
He added: "If the DUP stand their own candidate we will definitely contest the election, but if they support a community candidate who has Ulster Unionist values, we will go for that."
This puts him at odds with Basil McCrea and John McCallister, two MLAs on his party's liberal wing, who have stated that they would leave rather than countenance close co-operation with the DUP.
Martin McGuinness of Sinn Féin, who held Mid Ulster since unseating the DUP's Rev William McCrea in 1997, has stood down to devote himself to his job as Deputy First Minister. Like all Sinn Féin MPs, Mr McGuinness did not take his Westminster seat.
Mr Nesbitt said: "Both parties are trawling for a community candidate who would appeal to the broad unionist community and represent the constituency in Westminster."
His stance was warmly welcomed by Simon Hamilton, the DUP's director of elections.
"We want a unity candidate.
We have long advocated closer co-operation between unionist parties. There is much more uniting us than dividing us," he said. Mr Hamilton added that conversations had already taken place between the two parties at "both local and leadership level, and would now continue apace."
Two nationalist candidates have already declared, Francie Molloy of Sinn Féin and Patsy McGlone of the SDLP.
Willie Frazer, the victims' campaigner and flag protest leader, has also said he will stand. Mr Hamilton ruled him out as a possible unionist unity candidate. Mr McGlone said: "What the UUP choose to do is their business but you would expect an independent party to take its own independent decision to run its own candidate."
Mr Molloy said he was confident of winning the seat and accused the UUP of "copping out of running". He added: "This is a further sign of the decline of their party. They know they don't actually have a strong candidate in this area." Even against a single unionist, Mr Molloy is strong favourite.
Three of the six Assembly seats are held by Sinn Féin, which got 49.2% of the vote in 2011 compared with a joint unionist total of 31.9% spread among three parties, with the SDLP scoring 14.7%.
Bill White of LucidTalk, Belfast Telegraph polling partners, said: "Experience shows that the unionist vote is generally maximised when unionists have more than one party to choose from.
"I can't see the point of fielding a unity candidate in a seat where you can't win, it makes more sense for parties to field their own candidates so as to build their profile for the council and Assembly elections."