The NDP is calling on Patrick Brown to "do the right thing" and release a secret conversation between party brass and a would-be Hamilton PC election candidate.

The NDP made the call after a panel of appeal court judges sided with the PC's quest to keep it secret.

Gilles Bisson, the Ontario NDP house leader, says regardless of the court ruling, the Ontario PC head should unveil the secretly recorded exchange between campaign officials and Vikram Singh of Dundas. Singh wanted to be the Hamilton West-Ancaster-Dundas provincial PC candidate, and is now fighting the party in court.

Brown and the NDP have called on the Liberals to be transparent in their own court battles, including the gas plants scandal, Bisson said. So Brown should do that too.

"It shouldn't take a judge's order for Mr. Brown to do the right thing."

The statement comes after a months-long court battle between Singh and the party, in which the party has spent more than $245,000 trying to keep the recording under wraps.

Ontario MPP Gilles Bisson argues that Patrick Brown has called on the Liberals to be transparent in their own court cases, but isn't doing that now. (Michelle Siu/The Canadian Press)

Singh vied for the Hamilton West-Ancaster-Dundas provincial PC nomination last year. He alleges party officials stuffed the ballot box so Ben Levitt, a staffer in Conservative MP David Sweet's office, would win.

Singh and another would-be candidate, Jeff Peller, unsuccessfully asked the party to review the nomination. Then both asked the courts for a judicial review. Peller later dropped his case.

Singh, meanwhile, secretly recorded an in-person meeting he had with party brass last year. This includes "frank statements" by campaign chair Walied Soliman, the ruling says.

The conversation, Singh's lawyers submitted, implied Brown "had significant involvement" in the nomination outcome. The three-judge panel didn't agree.

"I do not agree that the impugned statements go that far," wrote Justice Laurence Pattillo.

The ruling, issued Jan. 19, appears to put Singh on the hook for $181,000 in total legal costs.

Hamilton police said last month that it's also interested in the conversation. Police are conducting a criminal investigation into possible ballot box stuffing.

Last week, Ontario's Ministry of the Attorney General asked the Public Prosecution Service of Canada (PPSC) to handle the case to avoid any conflict of interest.