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By Enda McClafferty
BBC News NI political editor
Democratic Unionist Party (DUP) leader Sir Jeffrey Donaldson is set to raise the stakes in his party's battle against the Northern Ireland Protocol.
In a keynote speech on Thursday, he is expected to issue a warning about the future of Stormont's institutions.
He is expected to signal his party's willingness to walk away from government if the DUP's demands on the protocol are not met.
Sir Jeffrey is also expected to harden against north-south engagement.
The speech comes as the European Commission Vice President Maroš Šefčovič begins a two-day visit to Northern Ireland during which he will hold talks with political and business leaders.
The UK and the EU are at odds over the Northern Ireland Protocol.
The protocol keeps Northern Ireland in the EU's single market for goods.
It prevents a hard border with Ireland, but some products need to be checked as they arrive into Northern Ireland from Great Britain.
Not all the checks have been implemented due to what are known as grace periods.
Earlier this week the UK government indefinitely extended the grace periods which it said was necessary to create space for further talks with the EU.
Speaking ahead of Thursday's speech, the DUP leader warned that in the "absence of actual progress, we cannot remain in this political limbo".
In a statement he said the protocol "is not just a threat to the economic and constitutional integrity of the United Kingdom, it is having real world impacts on our economy".
'A significant hardening'
He said he plans to set out the party's next steps to remove the protocol but provided no further detail.
But a senior DUP source said this will mark a "significant hardening of the DUP position and will place the onus on London and Brussels to act or run the risk of dragging Northern Ireland backwards, all the progress made from 2007 will be lost".
It is not clear if the DUP threat over its future involvement in power sharing will include a timeline or deadline for its demands on the protocol to be met.
But it is understood the party will adopt a tougher stance on north-south engagement which may involve boycotting future ministerial meetings.
In his statement on Wednesday night, the DUP leader said three key issues must be addressed including the movement of goods, standards and governance.
"This is not simply a question of limiting checks at the border or moving checks from the border. It must mean that, save for the most limited circumstance EU law would not apply in Northern Ireland".
He added: "It must mean that where there is a dispute we are not being asked to argue our case in front of a judicial system created by one of the parties to that dispute."