"One example is the long-gun registry, where there has been no real compromise at all; Mr. Mulcair has made it clear he will bring back the long-gun registry and will use the whip," said Bruce Hyer, who will now sit as an Independent MP for Thunder Bay Superior North.

"I am also concerned that Mr. Mulcair does not seem willing to co-operate with other parties on important issues."

Hyer was first elected to the northern Ontario riding in 2008.

The registry is largely loathed in rural and Western Canada.

"This demonstrates that there is one part that represents rural and northern Canadians along with all law-abiding hunters and sport shooters," Public Safety Minister Vic Toews said.

The newly minted NDP leader from Quebec said Hyer is sulking.

"He didn't get a shadow cabinet role," Mulcair said. "He simply doesn't believe that you ever have to follow the decisions that have been taken by the group. Bruce feels that he is allowed to come up with his own decisions."

"It demonstrates that life in Mulcair Land is not as sweet as some would think," Liberal MP Ralph Goodale said, adding that there are no talks between the Liberals and Hyer.

The NDP lost another MP in January when rookie Quebec MP Lise St-Denis quit the party to join the Grits.