OTTAWA -- A Federal Court judge on Wednesday asked the second arbitrator in the dispute between Canada Post and the Canadian Union of Postal Workers to step aside.

Judge Daniele Tremblay-Lamer asked Guy Dufort to abandon his post as arbitrator, saying he was biased due to his ties to the Conservative Party and his having represented Canada Post in the past.

"This decision shows that we have been right to oppose this flawed process," CUPW national president Denis Lemelin said.

Dufort, a retired labour lawyer, was appointed by Labour Minister Lisa Raitt in March. After his appointment, Dufort submitted his resume to the CUPW. Dufort ran for the Conservative party twice and advocated for the Canada Post Corporation between 1998 and 2003.

CUPW requested Dufort not be the arbitrator but in April he refused to recuse himself on the grounds his partisan activity stopped in 2010.

"CUPW provided Mr. Dufort's name on their short list of potential arbitrators put forth in Novermber 2011," a spokesperson for Raitt wrote in an e-mail.

CUPW has written to Raitt and asked a mediator be appointed to facilitate collective bargaining, rather than someone with whom she is friends with on Facebook.

The union found both Raitt and Steven Fletcher, minister of transport responsible for Canada Post, to be friends with Raitt on the social networking website.