John Swinney has been urged to extend the £2 bus fare cap to the rest of Scotland by the end of the year.
Scottish Greens co-leader Ross Greer said the First Minister must follow England with a nationwide cap.
The Scottish Government has pledged to rollout the £2 cap for all of Scotland by 2031.
Speaking during First Minister’s Questions, Mr Greer said England already has a nationwide cap in place, and he urged Mr Swinney to move sooner to introduce one north of the border.
He said: “The Green’s pushed for and we secured the £2 bus fare cap across the Highlands and islands. That’s now been extended to the west of Scotland.
“But the Government says it could take up to five years for £2 bus fares to reach the rest of Scotland.
“That surely can’t be right. People need help right now.”
Mr Greer said the cost-of-living crisis is “crushing” Scots, including rising prices at the pump.
He said a bus fare cap has already been in place in England and from January fares will be limited to £2.
“Commuters in Scotland are struggling with their costs just as much as those in England,” he said.
He said many passengers are paying a “small fortune” for their commute.
He added: “Is the First Minister really saying it’s impossible to bring the £2 bus fare cap in across all of Scotland by January, in line with England?”
He also said cheaper fares “made it more urgent” that buses are put back under public ownerships, saying: “We can’t let the good work that we’ve done making buses cheaper for passengers result in more money landing in the pockets of self-proclaimed billionaires like the Easdale brothers.
“So, will the first minister extend the £2 bus fare cap to the rest of Scotland by the end of this year and help more people save money on their commute?”
Mr Swinney said the Government wants to extend the cap to the rest of Scotland “as quickly as we can do”, and he pledged to work on progress at the next budget in December.
The First Minister said while England has a bus fare cap, peak rail fares have not been abolished and there is no universal free bus travel for under-22s.
He said: “We’ve got to take the decisions in an orderly fashion as quickly as we possibly can do – I’m signalling my willingness to do that.
“We’ve just rolled out very quickly after the election, as we said we would do, delivered on our promise to roll out the £2 bus fare cap to the west of Scotland.
“I would hope Mr Greer could look at the progress the Government has made and take confidence in the fact that the Government is determined to deliver.
“There’s a lot happening under the Scottish social contract delivered by the SNP already – and it’s good news for the people of Scotland.”