Scottish Labour is calling for free bus travel to be protected by law for people aged over 60.
The party’s transport spokesman Colin Smyth is to put forward legislative amendments when Holyrood returns from recess.
If adopted, they would see the right for all over-60s to a free bus pass written into law, with the qualifying age put into legislation for increased protection.
Mr Smyth said: “Sadly, the scheme is now under threat with SNP ministers refusing the rule out increasing the age citizens can qualify for a pass in a bid to try and save money.
“Ordinary people in their 60s should not be paying the price of Tory austerity because the SNP refuse to use the powers of the parliament to fund our services properly.
“That is why Labour will table amendments which would enshrine the qualifying age for older people into law if passed by parliament.
“Labour will continue to fight for a publicly owned transport system that works for the many, not just the few.”
A devolved Labour-led government introduced the free bus pass for the over-60s in 2006.
The party now also wants to see free bus travel extended to others including modern apprentices and companions travelling with disabled children.
A public consultation, which ended in November, was carried out on the future of the bus pass including raising the age of eligibility from 60 to 65.
A Transport Scotland spokesman said: “We are already committed to providing free bus travel for older and disabled people and everyone who has a bus pass will keep it.
“We analysed nearly 3,000 responses received to our recent public consultation on possible changes to the scheme and are considering what respondents have said.
“As previously outlined in our consultation on concessionary travel, we are considering free bus travel for modern apprentices alongside the provision of companion cards for eligible disabled children aged under five who are not currently covered by the scheme.
“We are committed to supporting services and tackling the historic decline in bus passenger numbers.
“The Transport (Scotland) Bill aims to give local authorities the flexibility to pursue partnership working, local franchising, or running their own buses in certain circumstances, allowing local authorities to better respond to local needs.”