Arlene Foster has denied threatening the Prime Minister over Brexit, insisting she does not think Theresa May would even consider a deal that would treat Northern Ireland differently.
Weekend comments by the DUP leader about the party's "red line" on customs arrangements post-Brexit were interpreted by some as a veiled threat to pull the plug on her party's confidence and supply deal with the Tories.
Mrs Foster said she was simply reiterating the DUP's long-standing position - that Northern Ireland must be treated the same as the rest of the UK in the exit deal.
She had been asked about the issue amid speculation that Brexit Secretary David Davis was considering proposals that would see Northern Ireland covered by a joint regime of UK and EU customs regulations, allowing it to trade freely with both, plus a 10-mile wide "special economic zone" on the border with Ireland.
That idea was subsequently dismissed by Downing Street.
On Monday, Mrs Foster said her remarks about the party's red line was not a threat to Mrs May.
"I don't characterise it as a threat," she told the Press Association.
"Our red line is there, it's open, everybody has heard me say it on many, many occasions.
"We will judge any proposition against that red line.
"Frankly I was a bit surprised that it was characterised as threat."
Mrs Foster was attending the launch of a report at Stormont that examined the impact of one of the key planks of the DUP's £1 billion confidence and supply agreement with the Conservatives - a £150 million investment in broadband coverage in Northern Ireland.
She said her party had not been presented with any papers from the Government that suggested treating Northern Ireland differently.
"I know that Theresa May and her team are very cognisant of the fact that is our red line and that's what we are working on," she said.
"She knows what our position is, she's known it all along, so therefore I have no reason to doubt that she wouldn't move away from that."
Cabinet ministers were last month tasked with analysing the two main options so far put forward for the Irish border, a "customs partnership" proposal that would see the UK continue to collect tariffs on behalf of the EU and the technology-based "maximum facilitation" - or "max fac" - solution.
Mr Davis's mooted idea was dubbed "max fac 2".
Brussels has already rejected both schemes, with chief Brexit negotiator Michel Barnier saying on Friday that neither was "operational or acceptable".