Opposition to the B.C. carbon tax has cost provincial New Democrats at least one high-profile member.

Environmentalist Tzeporah Berman has sent a letter to NDP Leader Carole James saying she's giving up her membership and won't be voting for the party when the province goes to the polls on May 12.

Berman says the NDP support for a cap-and-trade system to reduce greenhouse gas emissions doesn't go far enough and the party's opposition to the carbon tax plays "fast and loose" with climate politics.

She says last year B.C. New Democrats voted against cap-and-trade in the legislature and she says the party's carbon tax policy is an attempt to "confuse the public" for political gain.

"You have put politicking before the planet in the most hypocritical fashion," Berman wrote to James, according to a front page article in today's Vancouver Sun.

Berman – who has become an increasingly divisive force within the B.C. environmental community – stopped short of endorsing Gordon Campbell's B.C. Liberals, who implemented the escalating carbon tax on fossil fuels last year.