The 2009 exchange, which was played at the Charbonneau Commission on Tuesday, is between two senior union bosses — then-FTQ president Michel Arsenault and Jean Lavallée, a former president of the FTQ's construction wing.
In the wiretapped evidence, recorded in 2009, Arsenault is heard saying that he'll "talk to Pauline" about it.
Marois was the leader of the official opposition at the time.
Marois has denied the allegations, saying that she long ago decided that her party would ask for an inquiry.
"There never was a deal, and there isn't a deal," Marois said.
The Charbonneau commission continues today, with more testimony from Lavallée.