Stormont's devolved government is "dysfunctionalism on stilts", the leader of Traditional Unionist Voice (TUV) is to tell his party conference.
Jim Allister will also reiterate his party's long-held concerns over the impact of post-Brexit trade barriers between Northern Ireland and Great Britain.
Northern Ireland will be "sleepwalked out of the United Kingdom" if the Irish Sea border remains in place, he is expected to say in his speech on Saturday.
Among the scheduled speakers at the event in Cookstown, County Tyrone, is the Reform UK MP Danny Kruger.
Since Brexit, Northern Ireland has continued to follow many European Union trade and customs rules to avoid a hard land border with the Republic of Ireland.
The arrangements were agreed between the UK and EU under deals known as the Northern Ireland Protocol and later the Windsor Framework.
But unionists have raised concerns that the rules - which have involved extra trade checks and paperwork for goods coming from Great Britain - undermine Northern Ireland's place within the UK.
Stormont's power-sharing executive had been blocked by the Democratic Unionist Party (DUP) in protest, but they ended their boycott in 2024 after a deal with the UK government.
In his conference speech, Allister is expected to say "there should be no executive as long as the protocol exists".
"Leave the protocol and the dopes in Stormont in place and we will be sleepwalked out of the United Kingdom," he will say.
"Even President Trump can see it as he jokes about a merger."
Allister will say the "dud" deal between the DUP and UK government in 2024 has "cemented the protocol".
The TUV leader will also describe the Stormont institutions as "dysfunctionalism on stilts".
He will argue they involve a "legislative assembly that doesn't legislate - apart from their own salary rise".
Allister will also criticise the DUP sharing power with Sinn Féin as part of Northern Ireland's four-party executive.
"The choice is not Stormont or soon to be gone Starmer, but enabling Sinn Féin or dumping Sinn Féin - pandering to Sinn Féin or facing down Sinn Féin," he is expected to say.
On the issue of cooperation with other unionist parties, he will say "unionism should be united" in opposition to the "iniquitous protocol".
"It is not those of us who have stood firm who need to return to the ground of unity, but those who stepped away."
The TUV has one MP and one assembly member at Stormont as well as elected representatives at local council level in Northern Ireland.
Allister became MP for North Antrim in the 2024 general election, unseating the DUP's Ian Paisley.
Earlier that year, TUV agreed a formal "partnership" with Reform UK for the general election.