The goal is said to be a new, non-sectarian, civic unionism. When the Ulster Unionist Party chose to link up with the Conservative Party, it did so in order to advance this objective - the creation of a broader unionist movement which would attract Catholic votes.
At least, if that is not what non-sectarian unionism means, then it doesn't mean very much. But who came up with the strange idea that significant numbers of Northern Ireland Catholics would suddenly find the Ulster Unionist Party more attractive when it was in partnership with the Tories, another party they have little inclination to vote for?
They were right about one thing: there are, indeed, many unattached Catholics out there.
They do not vote for Sinn Fein, perhaps because they do not forgive the party that endorsed the IRA campaign and they have given up hope on the SDLP as a party that can participate significantly in government, or in the Northern Ireland Executive, even.
Many of them, in their hearts, would like to see Ireland united some day, but, if they were called to vote in a referendum tomorrow, they would vote against unification - if only because they would not want to be part of the economic catastrophe that they see south of the border.
The Catholic voting tendency is divided between heart and head. These same people may prefer to think of themselves as left wing, in British terms. They will not vote for the Conservatives because they never have done.
That has not very much to do, really, with economic thinking; it is just that the Tories are the traditional enemy and crossing the floor to embrace them would involve the same kind of change of heart as voting Ulster Unionist would require anyway.
This is not true of all of those Catholics whose votes are going spare.
Certainly, some will be comfortable voting for Cameron's Conservatives, but they will not have needed Reg Empey to suggest the idea to them, nor will that idea have any greater weight for having an Ulster Unionist endorsement.
Some Catholics will even vote for the Ulster Unionist Party. They will do so for a range of motives - the tactical desire to reduce the influence of the Democratic Unionist Party, loyalty to a local representative who has come to mean more to them than the party itself.
Many Catholic voters in North Down, for instance, have been voting for Lady Sylvia Hermon out of a sense that she is a good constituency MP and a decent and likeable person. But those voters are going to stay with Lady Sylvia when she runs as an independent.
The irony for the Ulster Unionist Party is that the very strategy which was meant to bring Catholic voters on board will have cost them many of the Catholic voters they already had.
Tonight the North Down Constituency Association of the Ulster Unionist Party will choose an alternative candidate to Lady Sylvia.
This will not be a candidate who will be immediately familiar to Catholic voters. Indeed, it may well be a person without trace of sectarian thinking or animosity.
The party's fight for the Catholic vote, through this candidate, will be as hard as ever. Linkage with the Conservatives will not turn that struggle into a soft sell.
What that linkage has achieved is the continued marking of distance between the Ulster Unionists and the Democratic Unionist Party. Those who want non-sectarian politics in Northern Ireland will be pleased with that.
The Democratic Unionist Party is working for the creation of a monolithic unionist bloc which will retain the office of First Minister. Unionists who resist absorption into such a bloc are more likely, in time, to find themselves building allegiances with other parties outside unionism; the SDLP or the Alliance Party, or both.
But there is a lot more work to be done inside the Ulster Unionist Party before many Catholics will feel comfortable actually joining it.
Unionists are right to intuit that the retention of the union is the embarrassing secret desire of many people in Northern Ireland who would never actually call themselves unionists.
Some have merely reconciled themselves to the unlikelihood of united Ireland. Everything in their lives which has practical meaning is based in Northern Ireland and within a British context.
If they retain a sense of affinity with the Republic, this, in itself, may be grounded in their own unfamiliarity with it; their not knowing how little interest the Republic has in the North.
And some, even among SDLP voters, believe deeply that working for a united Ireland depends first on securing better relations between Protestants and Catholics in the North.
Pitching a million disgruntled Protestants into united Ireland would be like bringing a bull to the opera; you wouldn't get to see the show.
But why will these people not join a unionist party - even if, occasionally, they will tactically vote for one?
It is because unionism is bedecked with cultural trappings, reverence for the monarchy, nostalgia for Empire and suffused still with a sense that the true unionist is a true Protestant.
The way to create a civic unionism was not to marry a British party which shared much of that baggage; it was to start throwing the baggage into the sea.