The US congressman Richard Neal has defended his use of the term "planter” after a negative reaction from unionist leaders.
Mr Neal was speaking during a visit to Londonderry on Wednesday, along with an eight-member US delegation.
He called the problems with the protocol “significantly disproportionate” to those experienced during the Troubles, and urged the UK and EU to find a way forward.
“People here took up much more severe challenges ... this is an issue for the European Union and for the UK government to sift and sort,” he said.
“I think we want to be mindful of the fact that the difference of opinion that existed from Brussels and London was substantial, and the commission in the European Union, they suggested these problems were imminently solvable, and I think based on the conversations we had of good faith that is the case.”
Despite criticism from unionist leaders in recent days, but Mr Neal said he was looking forward to a meeting with the DUP leader Sir Jeffrey Donaldson.
“I have known him for a long period of time, I don’t want to trespass. I have had a good relationship with him over the years,” he said.
Mr Neal was also asked about negative reaction to the use of the term “planter” when referring to unionist heritage and ancestry.
He maintained he was using a historic reference to the plantation during the 17th Century.
“That was the point that I made,” he said.
“I also referenced the historical term of the gael, the gael and the planter, because those are entirely accurate historic references.”
The Ulster Unionist leader Doug Beattie called Mr Neal’s comments “ill-judged”.
“He has got it completely wrong and rather than charging around like a bull in a china shop, he needs to stop, pause, listen and reflect,” he said.
“The issues around the Protocol are in no way manufactured, indeed they have been known about and discussed at every level since we raised them in October 2019.
"For Richard Neal to suggest they are, demonstrates a lack of understanding of the damage which the Protocol is doing and that he is somewhat removed from the reality of the situation.
“His comments which refer to people as ‘planters’ are derogatory to many unionists. His thinking and terminology are of a time past. We have friends in the United States which we need to engage with more and Congressman Neal`s biased view of the past and the present, are not representative of American diplomacy. It`s time that those with influence in the US, Irish Government and EU called on him to temper his ill-judged and unhelpful comments.”
Mr Beattie is due to meet Mr Neal and his delegation on Thursday, and said he hoped they would be “open to listening and reflecting”.
Earlier, the former DUP leader Arlene Foster said Mr Neal was a "long-time Sinn Fein supporter” who would say “armageddon” would occur if the protocol was changed.
Writing in The Express, Mrs Foster said that Mr Neal had previously planted trees in memory of IRA hunger strikers.
She added that he had also supported the President of Ireland, Michael D Higgins, who had “snubbed” church leaders by refusing to attend a church service in Armagh marking 100 years of Northern Ireland.
“Hardly surprising when you know that Neal stated that Northern Ireland was not a reality but was a boundary set up by military force,” she said.
“In his one of his latest offerings, Neal boasted about the changing demographics in Northern Ireland, in that there will soon, in terms of religious denominations, be more Roman Catholics than declared church going Protestants.
“According to Neal’s thinking that means that a United Ireland is inevitable because more Roman Catholics means more people who want to abolish Northern Ireland.”
Mrs Foster called this “base sectarianism” which was factually incorrect.
Mrs Foster said she attended many events in Washington were unionists had to endure “Brits out” slogans at black-tie dinners.
She added: “And let’s be honest, for too long the UK Embassy in Washington has allowed this rewriting of what happened in part of the UK, without challenge and that is so shameful and hugely damaging.
“So, there you go, this is the man who is leading a cross party delegation to tell the Brits what to do.”
Mrs Foster continued: “Since 2019 Richie Neal has also been the powerful Chairman of the Ways and Means committee in Congress, second only to Speaker Pelosi in seniority, but that doesn’t prevent him from showing his partiality.
“The delegation Richie Neal leads has been to Europe, simply to strengthen EU resolve against the UK proposals, (as if that were needed).”