Democratic Unionist MP Ian Paisley is facing a 30-day suspension from the House of Commons after his failure to register two family holidays paid for by the Sri Lankan government.
Mr Paisley had already apologised for what he said was his “unintentional failure” to register the hospitality, which he estimated was worth £50,000.
The sanction recommended by a parliamentary watchdog on Wednesday could see Mr Paisley face a by-election.
Members who are suspended from the Commons for more than 10 days are open to a recall petition.
A by-election would be triggered if 10% of the electorate in Mr Paisley’s North Antrim constituency sign that petition.
If rubber stamped by Parliament, the suspension will also mean Prime Minister Theresa May will be shorn of one of the 10 DUP MPs propping up her minority government during a period that could see a number of crucial Brexit votes in the House of Commons.
The sanction was outlined by the House of Commons Standards Committee following receipt of the findings of an investigation by the Parliamentary Commissioner for Standards.
The committee said Mr Paisley, son of late DUP founder the Reverend Ian Paisley, had committed “serious misconduct” and his actions “were of a nature to bring the House of Commons into disrepute”.
The report, which said the cost of the hospitality may have been “significantly more” than Mr Paisley’s £50,000 estimate, said the Sri Lankan holidays in 2013 included business-class air travel, accommodation at first-class hotels, helicopter trips and visits to tourist attractions for the North Antrim MP and his wider family.
The trips also included meeting with Sri Lankan governmental figures.
The threshold for registering such hospitality in 2013 was around £660.
In March 2014, Mr Paisley wrote to the then prime minister David Cameron to lobby against a proposed United Nations resolution setting up an international investigation into alleged human rights abuses in Sri Lanka.
The committee noted that in his letter the MP did not declare the financial benefits he and his family had received from the Sri Lankan government during the previous 12 months.
The watchdog’s finding read: “In view of the seriousness of this matter, we recommend that Mr Paisley be suspended from the service of the House for a period of 30 sitting days starting on 4 September 2018.”
It was recommended that Mr Paisley should also now register the holidays with the parliamentary authorities.
The recommendations will need to be approved by the House of Commons before being confirmed.
Mr Paisley is due to address the House on Thursday.
The story was first reported by the Daily Telegraph in September 2017, in a report which estimated the cost of the hospitality at £100,000.
A statement issued by Mr Paisley’s lawyer on Thursday said: “My client has apologised unreservedly at the outset for his unintentional failure to register the hospitality he received.
“While accepting the decision of the House Standards Committee, he nonetheless continues to take issue with the sensationalised report in the Daily Telegraph.
“Legal proceedings are being considered.
“No further comment will be made until Mr Paisley has addressed the House on Thursday.”