Jeremy Corbyn will pledge to protect the free bus pass as he meets pensioners on the latest leg of his tour of Scotland.
The UK Labour leader will be in Fife where he will restate his party's commitment to the concessionary travel scheme the day after a consultation was launched on raising the age at which Scots can obtain the bus pass.
The Scottish Government is proposing to increase the age of eligibility amid rising numbers of older people and a £9.5 million budget cut for the scheme.
On the fourth day of his visit to Scotland, Mr Corbyn will also promise a Labour government would keep the triple lock on state pensions and protect the winter fuel allowance after Tory plans to means-test the benefit south of the border.
Mr Corbyn, who will take afternoon tea with pensioners in Kirkcaldy, is expected to say: "Labour will extend the welfare state from the cradle to the grave.
"People who have spent their lives paying into the system deserve something back.
"That is why Labour will protect pensioner incomes by legislating to keep the triple-lock on state pensions, protecting the pensions of over one million Scottish pensioners and guaranteeing them a basic income necessary to live a dignified life in retirement.
"We'll protect benefits like the free bus pass and the winter fuel allowance, and deliver £3 billion more for public services in Scotland, some of which could be invested in our NHS and in social care."
The UK Labour leader's visit to Fife is part of a tour targeting marginal seats held by the SNP.