FORMER Labor minister and ACTU president Martin Ferguson has hit out at trade union power within the ALP.
Mr Ferguson's critique came as the union movement waits for a critical decision about the future of the Royal Commission into Trade Unions.
Justice Dyson Heydon, under pressure after accepting, then declining, an invitation to speak at a Liberal Party fundraiser, has reserved his decision on the ACTU's application for him to recuse himself from leading the commission.
It means he won't announce his decision until a date "yet to be set".
In an interview with ABC's Four Corners, Mr Ferguson refused to "damn" the commission, saying it would be crucial to reforming unions and Labor.
He said the Senate had become a "retirement pasture" for former unionists and the union movement now had a "stranglehold" on preselections for lower house seats.
Mr Ferguson said it was as if unions on the right and left wings of the Labor Party were "(dividing) the cake" of preselection for safe seats.
Similar comments earlier this year from the former Rudd and Gillard government minister, who now works as a lobbyist for the gas industry, prompted a call for his expulsion from the party.
Labor leader Bill Shorten supports the commission continuing, but without Justice Heydon.