DUP leader Arlene Foster has insisted her party is not dictating the UK Government's position on the Irish border in Brexit negotiations.
In an interview with Sky News, Mrs Foster rejected any suggestion she is holding the Prime Minister to ransom in Brussels talks, as a result of the DUP's deal with the Tories at Westminster.
She said: "That's not true. I don't think (her position) is solely based on her relationship with us as a result of the confidence and supply agreement.
"I fundamentally believe, and she has said many times, that she is a unionist so why wouldn't she want to preserve the constitutional position of Northern Ireland?"
Speaking in her rural Fermanagh and South Tyrone constituency, which overlooks part of the Irish border, Mrs Foster criticised the Irish government for demanding commitments from the UK before consenting to the next phase of Brexit negotiations.
"It's been quite aggressive in relation to Brexit and instead of looking for solutions…there's been a lot of megaphone diplomacy," Mrs Foster said.
The EU has demanded "sufficient progress" on key divorce issues - including the Irish border - before allowing Brexit talks to move on to discussions about future trade.
Mrs Foster also accused the Irish government of "cherry-picking" the Good Friday Agreement in its own interest.
She said: "The fundamental of the agreement is that we had the principle of consent, which essentially means that it is for the people of Northern Ireland to decide whether they want to stay within the United Kingdom or otherwise.
"We are part of the United Kingdom, a full part of the United Kingdom, and that shouldn't be forgotten by the Irish government.
"It certainly shouldn't be forgotten by the people in Brussels."
The Irish government wants Northern Ireland to remain in the EU's customs union to prevent changes at the Irish border, but the DUP insists it will leave with the rest of the UK.
Asked if she feared the Irish government holding out until they receive more clarity on the border, Mrs Foster added: "I think it would be very wrong if they exercised their veto.
"What we want to get down to is the detailed work in relation to the border and to our trading relationships and how it's going to work post-Brexit."
Mrs Foster will address her party's annual conference this weekend, five months after the DUP came to the aid of the Tories after they lost their Westminster majority at June's snap General Election.