Glenrothes SNP MP Peter Grant has revealed he intends to stand down at the next Westminster election.
The Fife politician admitted he was unsure whether he could cope with the demands of the role for another full term.
Mr Grant, 62, told voters he had made the tough decision after some “soul searching” as he would be nearly 70 after an extra five years in the job.
In a statement, he said: “Depending on the timing of the election the next parliament is likely to run until I am 68 or possibly 69-years-old.
“I owe it to everyone to ask myself whether I will be able to cope with the physical and mental demands of the job when I reach that age.
“I don’t think in all honesty I can give a firm yes to that question and that means in all conscience I can’t ask volunteers to campaign for me and ask voters to vote for me.”
Mr Grant – who also serves as the SNP’s Westminster treasurer – is now the second nationalist MP to confirm they won’t stand at the next election.
Former House of Commons leader Ian Blackford revealed earlier in June he will quit at the next UK-wide election months after he resigned from the top job.
Fife MP Mr Grant was first elected to Westminster in 2015 as the SNP turned Scotland yellow on a historic night for the nationalists.
He was swept into office as he gained nearly 20,000 extra votes in a seat which was traditionally one of Labour’s safest in the country.
Before that Mr Grant was a councillor in Fife for 23 years, serving as the local authority’s leader for the SNP between 2007 and 2012.
The Glenrothes MP said he intends to continue campaigning for independence and will strongly support whoever is picked to replace him.