The caucus chair of the NDP in B.C. has stepped down after a disagreement about how a fellow MLA was disciplined for criticizing the party's leader.

Norm MacDonald, MLA for Columbia River-Revelstoke resigned from his position Friday but will continue on as the opposition party's Forestry critic. The resignation will cost him more than $20,000 in lost pay.

Party leader Carole James told CTV News that MacDonald resigned because of her decision to expel Bob Simpson from the party caucus after he wrote a column criticizing the party leader's speech at a municipal government convention.

"Norm had a difference of opinion around the discipline of Mr. Simpson. He felt that a different kind of discipline could have been given," James said.

She dismissed speculation that MacDonald's resignation is a sign that the party is in turmoil.

"It's a good strong team," she said. "I continue to work well with Norm. We continue to work well around our caucus table."

Burnaby-Deer Lake MLA Kathy Corrigan has been appointed as acting caucus chair in the wake of MacDonald's resignation.