On Monday morning, accident-prone DUP politician Jim Wells tweeted: “Many complaints about Sinn Féin canvassing in Rathfriland yesterday. They are not welcome in this unionist town – particularly on a Sunday.”

This was, of course, an outrageous remark.

In a unionist town, nobody is particularly welcome – on any day.

But perhaps we should not be too hard on Wells, a South Down assembly member and Westminster candidate, because in this election his party has left him with little else to say.

Keeping Sinn Féin out, or more specifically off the top spot, is pretty much all there is to the DUP campaign.

Rathfriland, perched strikingly on a hill, might have made that priority seem almost visual.

The DUP’s official message for next week’s Westminster contest sets out three commitments, in the following order: restoring Stormont, getting the best Brexit deal for Northern Ireland and securing the union. All these pledges are clearly understood to mean beating Sinn Féin on a purely numerical basis.

The commitment to restore devolution gives this away. Why prioritise Stormont in a Westminster election, and by what mechanism would DUP MPs in the House of Commons put the assembly and executive back together again?

On Brexit, Northern Ireland’s voice will only be heard if the DUP and Sinn Féin agree a common position at Stormont, as London, Dublin and Brussels have made plain.

Brexit and Stormont

As for securing the union, this links unionist insecurity to Brexit and the collapse of Stormont, both of which have been opportunities for Sinn Féin.

Gerry Adams openly welcomed Brexit as a crisis not to be wasted, and the DUP has blamed him for crashing Stormont to capitalise on it.

The net effect of all these interconnected factors is that unionist voters see chaos all around and a Sinn Féin tide rising up the hill.

The DUP is telling those voters that stopping the republican momentum, or at least outpacing it, will put the world back to rights. Sinn Féin will realise it has milked as much vote growth as it can from opportunistic agitation and will return to the executive to manage Brexit as the DUP’s junior partner, with a few bones thrown to it on the Irish language and other demands.

This is the mechanism by which a Westminster success would translate into a Stormont result. It boils down to a headcount and nobody is pretending otherwise. The DUP only published a manifesto yesterday, eight days before polling. The party offers no concrete policies that link sending MPs to London with getting ministers back in Belfast.

There is nothing inherently wrong with a unionist party seeking to eclipse a nationalist rival on unionist grounds alone. In Scotland, the Conservatives are tackling the Scottish National Party (SNP) on a “stop independence” platform.

The DUP’s strategy is likely to work on its own terms. Polling indicates it will marginally increase its share of the vote, while Sinn Féin’s share will not change compared to March’s shock assembly result, when only 1,100 ballots separated the parties.

Westminster seats

The DUP is predicted to hold all eight of its Westminster seats. Sinn Féin can at most increase its current four to seven, but none at the DUP’s expense.

So Arlene Foster’s party will inch a little further up the hill and keep its feet dry, for now.

But then what?

Northern Ireland is not Scotland. Its constitutional divide is a matter of ethnicity not opinion, so a purely numeric win in the face of opposing demographic forces is simply delaying the inevitable – keeping its headcount above water.

Surveying this hollow victory will quickly expose the lack of policy, vision and leadership to expand unionism’s appeal.

Foster has become a symbol of the leadership vacuum. In last year’s assembly election, she secured the DUP’s best-ever result with a personality-based campaign for “Arlene’s candidates”.

Now the candidates are being pushed to the fore as Foster becomes almost as gaffe-prone as Wells. She is still considered an asset in attracting unionist voters, yet is considered a liability in provoking republican voters.

The implication that Sinn Féin will roll over if its numbers stall also looks wildly optimistic.

Last year, the combined nationalist vote share in Northern Ireland appeared to have peaked for the medium term at about 36 per cent. Sinn Féin’s growth alone since has pushed it up to 40 per cent.

If that growth has topped out for now, republicans can just put it in the bank and use it as leverage for more Stormont compromises or as a stronger case to agitate around Brexit, especially for a Border poll.

Sinn Féin might go back into the executive but under no circumstances can it do so as the DUP’s “junior partner”. The gains and promises of the past few months mean its members and supporters would not stand for it.

Unionism may win this election, but it is no longer enough for it to have the biggest party. What it needs is to be big enough to say: “Welcome to Rathfriland.”