The incoming DUP leader has said getting rid of the Northern Ireland Protocol will be his top priority in the coming months.
Edwin Poots said he is planning a showdown with Prime Minister Boris Johnson and Taoiseach Micheál Martin within his first 90 days in office to try and resolve the post-Brexit trade arrangements.
Stormont's current agriculture minister also told the Sunday Life newspaper he will not attend north-south ministerial meetings until the protocol issue is resolved.
In a wide-ranging exclusive interview with the newspaper, Mr Poots discussed post-Brexit trade arrangements, reforming and rebuilding the DUP, working with other parties, the Irish language, and when his predecessor Arlene Foster should stand down as First Minister.
Mr Poots, who recently recovered from cancer surgery, defeated the DUP's Westminster leader Jeffrey Donaldson in the battle to replace Mrs Foster, who announced her resignation last month.
Mr Poots said he has requested a meeting with Mr Johnson over the contentious protocol.
He is also due to meet Northern Secretary Brandon Lewis over the matter.
"The protocol is by far the biggest issue," he told the paper.
"For me, this is not a unionist issue. This is a Northern Ireland issue. At the end of the grace period we are looking at 15,000 checks being applied on goods coming into Northern Ireland from Great Britain.
"On supermarket goods and the food that ends up in your corner shop, that is going to affect every consumer in Northern Ireland.
"98% of our drugs and medical devices come from Great Britain. Those are going to be subject to these checks after the scrutiny period and problems with getting things in, including cancer drugs.
"It is just entirely unacceptable that our health service could be hit with additional cost, and indeed with maybe not having certain material that is needed as a consequence of it.
"We need to find a solution which overcomes all of this. We need the EU to recognise this protocol is not fit for purpose. It isn't working and it cannot work and therefore we have to go back to the drawing board.
"We have more checks taking place between Great Britain and Northern Ireland than all of the eastern border of the EU.
"Goods that are staying in the UK in my view should not have checks. That is my ultimate goal."
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Mr Poots said the legal challenge he has threatened to take over the post-Brexit trading arrangements could go ahead in the coming weeks if the problems are not resolved.
It is separate to a judicial review being heard at Belfast's High Court in the name of unionists from across the UK, including Mrs Foster, UUP leader Steve Aiken, TUV leader Jim Allister and Belfast Agreement architect Lord Trimble.
"We are looking for judicial remedies to see if we can overcome some of those areas where officials believed they are bound by law," Mr Poots said.
"If there are grey areas and opportunities, we will certainly seek to strip away elements of the protocol. But ultimately it needs [to be] fundamentally changed [or] removed to take things forward."
He said he is happy to work with people on protecting the single market but "that does not involve what they have done in terms of creating this border down the Irish Sea and the consequences that flow from that for the individual in Northern Ireland".
He added: "I have been working with a senior UK lawyer who is advising us on what steps we can take in terms of judicial remedies.
"If there isn't real significant political progress made in the coming weeks, I would imagine we would be launching judicial proceedings in the not too distant future."
While he said he is determined to get the issue of the protocol resolved, in the short-term he is aware that unionists may have to wait until the end of 2024 until the Northern Ireland Assembly can vote on whether to continue with the arrangements.
Mr Poots also told the paper he has no intention of returning to north-south meetings until the protocol issue is resolved, and wants to meet the Irish Government over its handling of the issue.
He claimed the Government has "hugely damaged" north-south relations in its conduct over the protocol.
"They claim to be protectors of the Belfast Agreement yet they have allowed a coach and horses to be driven through it," he added.
Mr Poots also said he wants to speak with outgoing leader Mrs Foster about ensuring "a smooth transition" in the party's leadership.
Mrs Foster has said she will step down as DUP leader at the end of May and as First Minister at the end of June.
Mr Poots said he wants his new ministers to get "up and running".
He added: "We will obviously have conversations with Arlene about a smooth transition and I want our party to be a party that is healing and fit for purpose going forward.
"Therefore, I will deal with things as gently as I possibly can but also practically going forward.
"I will ascertain those views over the next few days."