The Democratic Unionist Party's Ian Paisley Jr could become the first member of the British Parliament to lose his seat under legislation brought in after a major scandal over expenses in 2009.
A recall petition has gotten underway in his North Antrim, which could spark a by-election if 10% of his constituents decide to back it.
Mr Paisley Jr has already been suspended from the House of Commons and the DUP over his failure to declare two luxury family holidays that were paid for by the Sri Lankan Government.
He has apologised to the House for his actions - admitting that he failed to properly register the holidays, but claiming he had "no ulterior motive for that genuine mistake."
The poll opened this morning - and constituents have six weeks to sign it.
Ian Paisley Jr with Arlene Foster after she became the new DUP leader, 17-12-2015. Image: Liam McBurney/PA Archive/PA Images
Virginia McVea, Northern Ireland's Chief Electoral Officer said designated polling locations have opened in Ballycastle, Ballymoney and Ballymena.
"Anyone who wishes to attend, who has been allocated to that designated place can go there," she said. "That process will continue through until September 19th."
Mr Paisley's suspension comes at a difficult time for the British Government.
The minority Conservative Government is currently propped up by the DUP's 10 votes under a confidence and supply arrangement.
With the October deadline for a Brexit Withdrawal Agreement looming ever closer, the loss of even one vote could cause a major headache for British Prime Minister Theresa May.
SDLP Leader Colum Eastwood said the people of North Antrim should not be afraid to vote for change.
"The people decide in elections," he said. "The people decide when it comes to these things and the people, I am sure, no matter what background they are from will be absolutely disgusted with somebody like Ian Paisley taking that kind of hospitality."
The holidays were originally reported by the Daily Telegraph which estimated their value at £100,000 (€112,000) - however Mr Paisley claims the cost was closer to £50,000 (€56,000).
Following the trips, he wrote to then-British Prime Minister David Cameron in support of the Sri Lankan government over a proposed UN resolution.
In the letter, he noted with alarm the UK Government's decision to "internationalise the internal affairs of Sri Lanka” and called on Mr Cameron not to support the UN resolution “internationalising” the conflict in that country."
In a report published last month, the Commons Standards Committee found that his actions amounted to "paid advocacy" and warned that he had brought the UK House of Commons into disrepute.
His House of Commons colleagues then voted in favour of a 30-day suspension from the house.
