A group of Labour TDs are due to meet tonight to consider an emergency motion which would all but block the sale of Aer Lingus.
The move could see an emergency motion tabled before the party's national conference this weekend, which may be binding on TDs.
Labour's deputy leader Alan Kelly says he's "not surprised" by the development.
If the motion is passed at the conference in Killarney, it could be binding on the party's TDs and automatically kill off the sale, as TDs would then have to break this instruction to vote in favour of the sale in the Dáil.
"We're a very democratic party. Many motions come through, and emergency motions," Minister Kelly said this morning.
"I'm not surprised there's such a motion," he said. "We'll be discussing it there,"
Meanwhile the airline's reported increased profits this morning - with the airline's incoming chief executive again arguing in favour of the deal.
Stephen Kavanagh says the Heathrow slots are worth less than €500 million - and that the number of potential job losses would be under 200, but that these would be reversed in time as the airline grew.
A group of Labour backbenchers will meet this evening to consider their options and finalise any emergency motion.
Our political correspondent Gavan Reilly filed this report for Today FM's National Lunchtime News:
