Trevor Ringland, whose voters will be crucial in deciding the battleground of East Belfast, yesterday said that he could not back the DUP.
Mr Ringland won 7,300 votes in the constituency as a joint Ulster Unionist-Tory candidate in 2010.
If it was Gavin himself no problem, but you are voting for the DUPTrevor Ringland
As an analysis of the seat in Saturday’s News Letter shows, neither the Alliance incumbent Naomi Long nor the DUP challenger Gavin Robinson can win without picking up a large proportion of Mr Ringland’s vote five years ago.
The News Letter asked the former Ireland rugby international how he would vote in this year’s contest.
“I said I would stay out of it,” he replied, adding that he was still involved with the Northern Ireland Conservatives and that neither the DUP nor Alliance “do it for me”.
Pressed on how he would vote in a straight Naomi-Gavin fight, with no other contestants, he responded: “That’s a good question.”
He went on to say that both were good candidates, and “the sort of people we need to see in the Province’s politics”.
Then he added the bombshell: “Taking the NI Conservatives out of it, and taking my desire to see normal politics out of it completely, I could not vote for the DUP.”
The comments are significant because they challenge the widespread assumption that in a unionist electoral pact, supporters of the Ulster Unionist Party in the greater Belfast area will automatically transfer to the DUP before the Alliance.
Such a calculation has been at the heart of the decision to run a single candidate against Naomi Long.
Mr Ringland did not explicitly say he would support Naomi, but when presented with a limited two-way contest, the only candidate whom he specified that he could not support was the DUP man.
Mr Ringland added: “If it was Gavin himself no problem, but you are voting for the DUP. To what extent would he be controlled by that narrow unionist position in the DUP?
“I don’t think my votes would automatically transfer to the DUP. The vast majority of people who vote for me don’t like the DUP, they have been about more constructive unionism.
“That is the contradiction about Gavin. He is a more constructive unionist but is in a party that is not a great example of that, to say the least, over the years. They don’t have the capacity to reach out beyond a certain type of unionist.”
Asked to predict where his 7,300 votes will go, he said: “I don’t know. A significant number might not bother voting. A significant number like me would not be able to vote for the DUP.”
But Mr Ringland was also critical of Alliance. “I want a party that is committed to putting Northern Ireland first, but is also about constructively arguing the constitutional question.”
He said the two candidates “should actually be in the same party promoting Northern Ireland first as part of the UK, but both want all of the people in NI to do well, with good relations across these islands”.