Ulster Unionist leader Steve Aiken has accused Boris Johnson of "damaging the Union" amid surging calls for a border poll.
Mr Aiken was speaking after Gordon Brown called on the Prime Minister to take action and save the UK from becoming a "failed state".
TUV leader Jim Allister echoed Mr Aiken's comments, saying the UK Government had made a "huge mistake" with the Northern Ireland Protocol and urged them to reverse it. Former PM Mr Brown was speaking after a Sunday Times poll found that the majority of people in Northern Ireland want a border poll within five years.
However, it also found that a majority of 47% would want to stay in the UK, with 42% in favour of a united Ireland and 11% undecided. He urged Mr Johnson to consider ideas such as replacing the House of Lords with a "senate of the regions" and to review how the UK is governed. Mr Aiken said he agreed with Mr Brown that there was a need to give power to the UK's regions and have them working together on the things that matter.
"If you consider the strands that hold the UK together, the NHS, the culture, the BBC, our armed forces, our education system, our universities, our system of finance and banking, we are much stronger together than split into smaller components part," the South Antrim MLA said. "That's something we should be building on, that should be the way ahead. I think Northern Ireland should be a shared home place for all of us within the context of the UK."
"When you look at Manchester or London, they are shared homeplaces between hundreds of identities. That's something to be proud of and something the UK should be aspiring to. "The one common denominator that is damaging the Union at the moment is Boris Johnson." He added: "I've got a lot of faith in the UK. I think it's a great place to live, but there's quite a few problems that need ironed out and that's what we should be working for."
Mr Allister said the Labour Government Mr Brown served in was responsible for many of the problems being experienced.
"Their big reform in encouraging devolution is the seed of much of the trouble. I think that Tony Blair and his surge towards devolution made a strategic decision in terms of the unity of the UK," the North Antrim MLA said.
Mr Allister also took aim at Mr Johnson's Government. "They needed to demonstrate we were leaving the EU as we joined, as one nation, and they failed," the former MEP said.