It's expected Fine Gael and Fianna Fáil will formally respond to the Green Party's letter on government formation today.
It's been 80 days since the general election and there's still little sign of a government being formed.
The Greens have made a 7 per cent annual reduction in carbon emissions a red line if they're to enter government.
TD Neasa Hourigan also says 20 per cent of the transport budget needs to be dedicated to walking and cycling.
"I think it's important that we stop thinking of walking and cycling as just exercise, or something extra that we do.
"We should be thinking of it as commuting, and as we move into a low carbon society, the idea of multi modal travel is going to become more important.
"So it's not necessarily that you don't have a car, or that you always use one mode or the other - it's where possible you try and walk or cycle."
