The Fianna Fáil leader Micheál Martin is claiming "unelected people" have undue influence over Sinn Féin policy.
Mr Martin made the claim as he gave his reasons for ruling out any future coalition with Sinn Féin.
He said that Sinn Féin initially welcomed the appointment of PSNI officer Drew Harris as the new Garda Commissioner.
However, Deputy Martin wonders why Sinn Féin leader Mary Lou McDonald changed tack.
Mr Martin said: "By 12 o'clock, Mary Lou had come full circle and was in attack mode on Drew Harris.
"I'd have to question did Mary Lou get a few phone calls from people in Belfast to say 'we want you to change tack in relation to that particular appointment'."