Tom Mulcair says former NDP MP Bruce Hyer’s decision to join the Green Party is “a betrayal of the voters” in his riding, and says he should resign and face his constituents in a byelection.

Hyer has been sitting as an independent since he left the NDP in April 2012 due to differences of opinion over NDP policy, including the vote on the long-gun registry. Hyer broke ranks with the NDP and voted with the Conservatives to scrap the registry.

Hyer, 67, was first elected MP for Thunder Bay-Superior North in 2008 and was re-elected in 2011.

In an interview with CTV’s Power Play Friday, Mulcair said “97 per cent of the people in Thunder Bay-Superior North didn’t vote for the Green Party.”

“It’s a betrayal of the voters in that riding by Bruce Hyer,” Mulcair said. “I knew he wasn’t reliable but now the people in his riding know that he’s not reliable.”

Mulcair accused Hyer of disregarding his own opinion that MPs who cross the floor should run in a byelection before joining another party.

“If Bruce Hyer were a man of his word, if he had any values whatsoever, he would resign, he would represent himself in front of his electors,” Mulcair told Power Play.

“We know what we would do. We would run somebody very strong and we would keep that riding because it’s a strong NDP riding. I don’t think he has the courage to do that.”

Hyer explained his decision to join the Greens in a statement, saying he would feel more free to represent his constituents without the strong party discipline that other MPs face.

“Becoming a Green Party MP will allow me to maintain my independence and stand up for the interests of my constituents. Working with the Greens, I’ll have access to the resources of a well-organized national party and will have the benefit of collaboration with Elizabeth May and her team,” Hyer said in a statement.

“My decision to sit as an independent was a response to the way the major parties limited true representation of my constituents by demanding lockstep discipline. This mindless solidarity prevents cooperation and compromise, meaningful policy discussion and finding productive solutions for Canadians.”

Green Party Leader Elizabeth May said she was happy to double the size of her party’s caucus.

“Bruce will be at home in the Green Party, as he has been a strong advocate on environmental issues since the 1970s,” May said in an email to supporters. “In fact, we both were organizers of the very first Earth Day.”

In the email, May said that “as a Green MP, Bruce will never face a whipped vote. It is the duty of a Green MP to balance the aims of the party as expressed through our policy, and the desires of our constituents as expressed through local consultation.”

Shortly after Hyer made his announcement, NDP ethics critic Charlie Angus criticized the move as “self-centred,” and “serves to fuel the cynicism that has driven voters away from Canadian politics.”

He, too, said Hyer should resign his seat and run in a byelection.