The free Dáil car park could be scrapped as part of the Climate Action Plan.
Taoiseach Leo Varadkar said he does not have a problem with removing the free lifetime parking perk for TDs and senators - if there are alternatives.
However, he added many rural TDs need to use a car to get to Leinster House.
Free public sector parking is set to be cut under the Climate Action Bill.
Environment Minister Eamon Ryan said that could be extended to parking at the Oireachtas.
'Scale of change'
Speaking in the Dáil, he said: "There are a lot of deputies who have to drive here, in reality, for their work... but there's a multi-storey car park just off Molesworth Street which is two minutes' further walk away.
"I don't see why we couldn't use such a facility on the Kildare Street side rather than to have everything parked right outside the front door. So yes it's going to be a scale of change, but it has to allow for the reality of people's everyday lives."
The revised Climate Action Plan, announced by the Government on Wednesday, will amount to nothing unless it delivers according to the Social Democrats.
The party said Irish carbon emissions rose by five per cent last year and are expected to rise by six per cent in 2023, despite government promises.
Social Democrats TD Jennifer Whitmore said the Government is already behind on retrofitting targets.
She told Newstalk: "This Government committed to retrofitting 500,000 homes to a B2 standard, which is a very high standard by 2030.
"They're probably looking at bringing in 3,000 to 4,000 retrofitting to B2 standard a year at the moment, there is not a hope in my opinion that they're going to meet the 500,000 target."
