Eight Labour TDs are expected to submit a motion raising concerns about IAG's bid for Aer Lingus at the party's conference this weekend.
The Irish Times reports that seven of the deputies are from Dublin - including Joe Costello - and one is from the mid-west and another from the east.
They are due to meet ahead of the conference today, before submitting the motion.
It is understood the TDs will demand that a series of "strict conditions" be met before Labour will consider supporting the Aer Lingus deal.