The Liberal members who make up most of the Commons justice committee agree in principle to look into the SNC Lavalin scandal, but, there’s disagreement among committee members over how far-reaching the investigation should be and who should be asked to testify.

Opposition MPs are demanding the prime minister’s most senior adviser, Gerald Butts, be called.

The Liberals rejected a request to draw up a proposed witness list for the committee in public, saying they prefer following normal parliamentary procedure and meet behind closed doors to select witnesses.

All Liberals on the committee also turned down a proposal from New Democrat MP Nathan Cullen to add the names of both Butts and Jody Wilson-Raybould to witness list.

The Liberals maintain they acted independently of the Prime Minister’s Office in agreeing to a probe but limiting its scope.

Opposition MPs are not buying it, calling it a ”cover-up”.

Wilson-Raybould resigned as attorney general and justice minister after she was allegedly pressured by the PMO to help SNC Lavalin avoid criminal prosecution.