On Friday, in the Orange Order’s heartland of County Armagh, Sammy Wilson MP got a taste of how deeply frustrated grassroots unionists in Ulster have become.

Several thousand people gathered in the small town of Markethill to express their anger at the Northern Ireland Protocol. The fiercely Brexiteer DUP politician would have expected a warm reception from this crowd, but instead he was booed and heckled.

Many pro-Union people in Ulster are angry that they have been cut off from the rest of the UK by the Irish Sea border. They feel let down by politicians who have failed to prevent Northern Ireland’s economic estrangement from Great Britain.

Ahead of an Assembly election in May, polls suggest that the DUP has lost support, with some of its backers considering switching to the moderate Ulster Unionist Party or the more hard-line option, the Traditional Unionist Voice. There is a real chance that Sinn Fein will become the largest party at Stormont, securing the first minister’s post and delivering a symbolic blow to unionism.

Yesterday, Michelle O’Neill, the republican party’s leader in Ulster, told Sky News that nationalists “are closer than… ever” to an all-Ireland state, claiming, “I think now is the time to plan.”

The idea that the Republic will soon absorb Northern Ireland is not credible. No serious opinion poll shows a majority for breaking up the UK. But, as the Protocol demonstrated, nationalist pressure can damage the Union, even if the constitutional position is not changed formally through a border poll.

Sinn Fein is already the largest party in the Dail Eireann, the Republic of Ireland’s parliament. Although the coalition government in Dublin has maintained its lead in polling, more than a third of Irish voters apparently want Mary Lou McDonald to head the next administration.

Many younger people, across the island, seem prepared to disregard Sinn Fein’s blood-drenched past, and they may even be attracted by a whiff of cordite. They ignore a campaign of murder directed overwhelmingly at their near neighbours, citing disaffection with the Irish government’s handling of issues such as housing and health.

Those of us who remember Northern Ireland’s Troubles find this shocking, but Sinn Fein’s political opponents must accept some responsibility for the situation.

When the DUP held the balance of power at Westminster in 2017, it had an unprecedented chance to contribute to the nation’s governance. Instead, it boasted that it had extracted £1 billion from the Treasury. Subsequently, it endorsed Theresa May’s “joint report” that entrenched the idea of a “backstop”. And it formally agreed to a regulatory border, though not a customs border, in the Irish Sea.

Now, the party’s attempts to overturn the Protocol seem increasingly futile. Northern Ireland agriculture minister, Edwin Poots, ordered checks on goods to stop at Irish Sea ports, but his directive was immediately suspended by a judge. The DUP collapsed the executive, when Paul Givan resigned as first minister, but that was only forty eight working days from the start of an election campaign. Before then, it had administered the Protocol.

Meanwhile, in the Republic of Ireland, Fianna Fail and Fine Gael have been ineffective in countering Sinn Fein’s propaganda. Their attempts to draw attention to the party’s past are undermined by almost six years spent attacking the UK during Brexit and Protocol negotiations.

Sinn Fein’s success has accompanied a surge of anti-Britishness that mainstream politicians like Leo Varadkar and Simon Coveney have contributed to and exploited.

Unionism’s malaise and Sinn Fein’s success is also nurtured by our own Government’s failure to deal with the Irish Sea border effectively. The Protocol has now been in force for over a year, preventing free GB to NI trade and raising costs in Northern Ireland, yet a solution to these problems seems no closer.

Unless Boris Johnson restores the province’s place in the UK’s internal market, or triggers Article 16, unionists will continue to look like losers and Sinn Fein will enjoy masquerading as a winner.