Jeremy Corbyn is "too old" to lead the Labour Party into the next General Election, figures in his shadow team have reportedly suggested.
Should Labour win an election in 2022, Corbyn would become the oldest ever prime minister to assume office for the first time, beating the record set by Viscount Palmerston, who was 70 when he entered Downing Street in 1855.
However, should he see out the whole five-year mandate, Corbyn would remain in charge until he is almost 78.
"A leader standing at a general election has to commit to doing a full five years," a shadow cabinet source was quoted as saying by the Independent.
"Jeremy is in good shape, but by May 2027 he will be nearly 78."
A senior frontbencher added: "Jeremy has a lot of energy now. But 2022 is a long time away, let alone 2027.
"Leading the country takes an incredible toll that is inescapable."
When, in July last year, the government announced the state pension age will raise to 68 over two years from 2037, Corbyn said that 68, his current age, was too old to still be working.
However, a spokesman for the Labour leader reiterated he remained committed to leading the party into the next election.
"As Jeremy has said, he's committed to leading the Labour Party into the next election, whenever that may be," he said.
Last month, the Labour Party leader predicted that a general election would take place in the next 12 months and that his party "will probably win" it.
In an interview with Grazia, Corbyn said that he was "ready to be prime minister tomorrow", a statement contradictory to his comments made at the Glastonbury music festival in June. At that time, he told the festival's founder and organiser, Michael Eavis, that he believed he would be prime minister by the end of 2017.
Earlier this month, the latest YouGov voting intention survey showed the percentage of Britons inclined to vote Labour at the next general election declined from 42% to 41%, while preference for the Conservative party remained unchanged at 40%.