A protest is being planned for outside the GPO in Dublin tomorrow, amid fears for the future of up to 200 post offices.
Weekend reports suggested An Post doesn't believe earlier proposals to shut 80 outlets would go far enough to cut costs.
The company has already announced plans to increase the cost of stamps.
Fianna Fáil's Communications spokesman Timmy Dooley said there are clear steps for the government to take.
"You identify the ones that aren't viable and then you work through those to identify the ones that are absolutely essential to ensure that you have a viable State service provision in a particular area.
"What also the government needs to do is put more businesses through those post offices that aren't viable."