The TUV is to stand a candidate in East Belfast in the upcoming Westminster election, increasing the pressure on DUP leader Gavin Robinson as he attempts to retain his seat.
The party, led by Jim Allister, announced its candidate team today.
They will stand under the TUV/Reform UK banner in 13 constituencies in the 4 July election.
Mr Robinson already faces a stiff challenge from Alliance Party leader Naomi Long in the East Belfast constituency.
He secured the seat by 1,800 votes.
He was confirmed as party leader this week, having taken over on an interim basis after Jeffrey Donaldson stood down in late March.
Mr Donaldson has been charged with sex offences which he denies.
The TUV/Reform candidate in East Belfast will be former British soldier John Ross.
Mr Allister said unionists who had been "astronomically betrayed" should be given the opportunity to show abiding opposition to the Irish Sea border.
He said: "East Belfast does not belong to any party.
"It's the people's seat and we're giving the people an opportunity to elect a stalwart who will stand strong.
"Who will not tell you one thing in February and tell you something else in July."
That is a reference to the DUP who sold their deal with the UK government that restored devolution as effectively removing the Irish Sea border.
Mr Robinson now concedes that what was achieved had been oversold.
Mr Allister said the TUV would not stand against the DUP candidate Carla Lockhart in Upper Bann because it risked handing the seat to Sinn Féin.
She was also said to be opposed to restoring Stormont on the basis of what had been agreed with the British government.
The TUV will not field a candidate in Fermanagh South where the Ulster Unionist Party will have a clear field to try and take the seat from Sinn Féin in what is always a hotly contested constituency.
The party is not standing in West Tyrone and Foyle where it has been unable to identify candidates due to the snap election.
It will also not stand a candidate in North Down where former DUP MLA, but now Independent Alex Easton is hoping to take the seat from Alliance's Stephen Farry.
Reform UK had intended to stand joint candidates but was not able to complete the necessary registration in time to be eligible for elections in Northern Ireland.
Mr Allister said Reform personalities would be out on the ground canvassing during the election.
