Sen. Mike Duffy attempted to influence the Canadian Radio-Television and Telecommunications Commission’s upcoming decision involving the right-leaning Sun News Network, a source has told CTV News.

A well-placed source told CTV’s Ottawa Bureau Chief Robert Fife that Duffy approached a Conservative insider with connections to the CRTC three weeks ago to discuss Sun Media, which is asking the federal regulator to grant its news channel “mandatory carriage,” or guaranteed placement on basic cable and satellite packages.

The move would boost Sun News Network’s profile and revenues.

“You know people at the CRTC,” the insider quoted Duffy as saying. “This is an important decision on Sun Media. They have to play with the team and support Sun Media’s request.”

Liberal MP Ralph Goodale said Duffy’s comments were “tantamount to saying: ‘Let’s go have a private little visit with a judge.’”

“That is direct political interference with a quasi-judicial tribunal,” Goodale said.

If the CRTC approves Sun Media’s request, cable and satellite customers across Canada will be paying to have its news channel as part of their TV packages.

“Helping insider friends to get access to power -- this is just unacceptable,” NDP MP Olivia Chow said.

Duffy, who quit the Conservative caucus Thursday night over a growing scandal involving his expense claims, did not respond to CTV’s request for comment.

He was secluded in his Prince Edward Island cottage -- the home he improperly claimed as his primary residence, resulting in a $90,000 debt to the Senate for repayment of wrongly claimed taxpayer-funded living expenses.

Fife revealed this week that Prime Minister Stephen Harper’s chief of staff, Nigel Wright, made a secret deal with Duffy to help him repay the money.

Although Duffy denied Wright’s involvement and claimed in an email to CTV News that he’d taken out a bank loan, the PMO confirmed that Wright wrote a personal cheque for $90,000 to the senator.

Canada's ethics commissioner, Mary Dawson, has said that she will investigate Wright's cheque to Duffy.