UUP leader Tom Elliott has sparked fury after attacking a joint plea against spending cuts by the First Ministers of Northern Ireland, Scotland and Wales.
Peter Robinson and Martin McGuinness teamed up with counterparts in Edinburgh and Cardiff to warn of “significant economic and social harm” unless the UK Government’s budget plans are changed.
The united front was condemned as “confrontational yet pointless” by the new Ulster Unionist leader.
The joint declaration spanning the UK's three devolved administrations was signed by Stormont Finance Minister Sammy Wilson, along with Mr Robinson and Mr McGuinness.
Also putting their names to it were Scotland's SNP First Minister Alex Salmond and the Labour First Minister of Wales, Carwyn Jones.
It pressed the coalition Government to rethink its push to swiftly and heavily cut public spending. While recognising the need for a “credible budget strategy”, they stated: “Frontloading the cuts into the next two years is entirely the wrong approach for the economy and the vital public services upon which so many people depend.
“We therefore urge that the spending cuts are scaled back and phased in over a longer time period.
“Failure to do so runs the risk of doing lasting damage to the economy and the fabric of our public services.”
Criticising the move, Mr Elliott said: “Peter Robinson has placed himself and the DUP firmly at the heart of a confrontational Celtic-nationalist fringe.
“People will rightly ask if aligning yourself with people who want to destroy the Union is the best way to work with an avowedly unionist Prime Minister.”
The UUP contested this year's General Election on a joint ‘UCUNF’ ticket with the Conservatives.
Mr Elliott has signalled the end of that arrangement, but is seeking to retain some relationship with the Tories.
He also said: “Northern Ireland has very specific economic and fiscal needs and I do not think those are best served by being lumped together with Scotland and Wales.
“I met with the Prime Minister and the Secretary of State this week and talked at length about the issues facing Northern Ireland — building relations and understanding I believe is the right way to get results.”
DUP MLA Simon Hamilton hit back, saying: “This is blatant nonsense from a man who leads a party aligned with the Tory cuts and who canvassed for Tory cuts.
“Tom clearly sees this issue as an opportunity to attack Peter Robinson for petty party political gain. Whilst Tom claims UCUNF is over, he's still quick to the defence of the Tories. I expect he will be equally as quick to defend the Tories cutting child benefits and gutting our capital budget.”