The Conservatives say they had no role in discussions with the DUP about the selection of Rodney Connor as a Unionist Unity candidate in Fermanagh and South Tyrone. So where does that leave the commitment by David Cameron that the Conservatives and Unionists would fight every constituency in Northern Ireland?
BBC Northern Ireland's Political Reporter Stephen Walker investigates.
David Cameron said Conservatives and Unionists would be running in all of Northern Ireland's seats
Some months ago I was talking to a senior Tory who is a keen supporter of his party's electoral link up with the Ulster Unionists.
We were having an amiable conversation about the forthcoming General Election. He reiterated his pledge that there would be a Conservative and Unionist candidate in every constituency in Northern Ireland.
When I suggested that it would be hard to resist pressure for a unity candidate in places like Fermanagh and South Tyrone our chat become more animated.
He raised his voice and told me in forceful terms that every seat would be contested and there was no way he would be party to a 'little deal with the DUP'.
In one sense he was right, as the agreement to endorse Rodney Connor in Fermanagh was negotiated between the Ulster Unionists and the DUP and it appears the Tories were left out of the discussions.
However, the outcome in the UK's most westerly constituency clearly runs contrary to David Cameron's pledge that every voter in the UK would have a chance to vote for him.
In fact, last autumn David Cameron told me in a television interview that Conservatives and Unionists would be running in all of Northern Ireland's seats.
Like military commanders who know that their well prepared battle plans often fail on the first point of contact, Cameron's troops have now been doing a little backtracking. It wasn't a retreat or a u-turn insisted Dominic Grieve, the Shadow Justice Minister as he campaigned in Northern Ireland.
He said his party was happy to accommodate Rodney Connor because he will take the Conservative Whip if elected to Westminster. He said this was an 'exceptional ' decision and said there was no question that they would stand aside in other constituencies.
However Rodney Connor's selection will inevitably raise the stakes in South Belfast for an agreed unionist candidate.
Although the circumstances are different, many Unionists will argue that if a deal can be done west of the Bann why not in inner city Belfast.
In fact those in favour of a South Belfast deal insist that such a move could be particularly attractive to Conservatives.
They argue that if the Cameron/Empey project is about putting people on the Tory benches at Westminster wouldn't it make sense to try and oust an SDLP MP who supports Labour.
However, privately some Conservatives are holding firm over South Belfast insisting that the Connor selection is 'a one off' and they will fight in all the remaining 17 constituencies as Conservatives and Unionists.
Both David Cameron and Sir Reg Empey know their electoral alliance is a new departure which comes with a great degree of risk.
Fermanagh and South Tyrone marked the first test of their battle plan for Northern Ireland.
Clearly the Unionist and Tory high command have taken some flak but like all military tacticians they must accept that sometimes you have to lose a few fights to ultimately win the war.