Mike Nesbitt does not rule out more joint candidates
Ulster Unionist leader Mike Nesbitt has refused to rule out fielding more joint candidates with the DUP in future elections in Northern Ireland.
On Thursday, Basil McCrea and John McCalliser quit the UUP over its decision to support a unionist unity candidate in the Mid-Ulster by-election.
Nigel Lutton was endorsed following DUP and UUP constituency meetings.
Mr Nesbitt said he would judge future strategy on the campaign results.
"Let's see how the next three weeks go," he told the BBC's Sunday Politics show.
"Will it work for the benefit of unionism and when we get the result from that and the answer from that, we can look at it.
"It would be foolish to rule anything out at this stage.
"We've just started a process which to some extent I certainly view as an experiment, let's see how well it works for the benefit of the unionist people."
Nigel Lutton's father Frederick "Eric" Lutton was killed by the IRA in May 1979.
The by-election on 7 March was called to replace Martin McGuinness.
Sinn Fein's candidate will be Francie Molloy and the SDLP candidate will be Patsy McGlone.
Eric Bullick is standing for the Alliance Party.
The decision by the UUP to support a single unity candidate led two senior members of the party, Basil McCrea and John McCallister, to announce their resignations.
Lagan Valley MLA Mr McCrea and South Down MLA Mr McCallister have not ruled out setting up a new party to challenge the UUP and DUP.
Mr McCrea said he could not stay in a party that was "heading towards a merger with the DUP".
Following the announcement of the joint candidate on Thursday, DUP leader Peter Robinson said the decision would be "welcomed by tens of thousands of unionists in both the Mid-Ulster area and more generally throughout Northern Ireland as a common-sense response to the demands to see unionists co-operating together".
Mr Nesbitt said the UUP had "listened carefully to the many pro-union voters in Mid Ulster who were calling for co-operation in this election and for the opportunity to end the long drought that has seen Mid Ulster without representation in the House of Commons for 16 long years".