DUP MP Sir Jeffrey Donaldson has said that MPs plotting to obstruct Brexit are "moving into very dangerous territory indeed".
Speaking to the Belfast Telegraph yesterday, Sir Jeffrey commented on reports in the Sunday Times that rebel backbench MPs are seeking to change Commons rules.
It would mean backbenchers' motions take precedence over government business - a move that could allow them to suspend Article 50, put Brexit on hold and potentially lead to the referendum result being overturned.
He said he "remains hopeful" that an "agreed way forward" can be secured.
"If parliamentarians think it's a good idea, and will strengthen our parliamentary democracy by seeking to overturn the will of the people by using some spurious device to change the rules of how Parliament conducts its business, then they are moving into very dangerous territory indeed," he said.
"I cannot believe that anyone who believes in democracy and who cherishes our system of parliamentary democracy would want to engage in such an action that would be about subverting the will of the British people.
"People are entitled to oppose the government, but what they're not entitled to do is to undermine the democratically expressed rule of the people."
Sir Jeffrey dismissed as "premature" suggestions that the Brexit leaving date should be pushed back as there are "still several weeks left until March 29".
Addressing reports that some MPs want to make it illegal for the UK to leave the EU without a Brexit deal, he added: "I remain hopeful that an accommodation can be achieved that enables the UK to leave with a deal - that's what we're focused on.
"We're not focused on the shenanigans that some parliamentarians who ought to know better are trying to engage in at this stage in order to frustrate Brexit."
He said a second Brexit poll would "make a nonsense of the concept of having a referendum" and, if the vote was pro-Remain, "it would be no time until we had a third referendum".
And he said he wasn't reassured by reports that the European Commission would shortly publish a letter emphasising the temporary nature of the contentious Irish border backstop. "We know that the backstop is temporary," he said. "The problem is that the backstop is indefinite in its nature and therefore there is a massive contradiction at the heart of the backstop - that what is supposed to be a temporary provision has no end date, and consequently we need changes to be made.
"Even if they were to give a letter, it's not legally binding. Whatever assurances are forthcoming from Brussels, they have to have clear, legal force."
Sir Jeffrey said his party would support Prime Minister Theresa May should she face a no confidence vote if Tuesday's Brexit vote goes against the government.
Commenting on ugly scenes involving protesters challenging some MPs outside the House of Commons, Sir Jeffrey said he had faced harassment "on many occasions" over his Brexit stance. "I've been in situations where you're doing interviews and there's heckling, playing loud music and there are people who crowd round, who push, shove and shout profanities," he stated.
"That is now a regular occurrence in the vicinity of Parliament. It's happening on both sides and it should stop. It didn't ever happen before Brexit.
"Harassment of any politician is wrong and I would call upon people, whether they support or oppose Brexit, to act within the law and to respect each other."
Mr Donaldson said he remains "hopeful that we can get an agreed way forward" over Brexit, adding that his party had made it clear to the Prime Minister "the deal in its current form is unacceptable".