Prime Minister Stephen Harper's environment minister is quitting politics to take a job in the private sector.

Jim Prentice made the surprise announcement the House of Commons, where he said he's accepted a job as a vice-chairman of the Canadian Imperial Bank of Commerce.

Prentice, 54, is stepping down after serving six years as a federal MP — the last four as a key member of Harper's Conservative government cabinet. He is frequently mentioned among the possible candidates who could succeed Harper as Conservative leader.

Harper told the Commons that Prentice has earned the "highest respect" of not just the prime minister, but of the entire House.

Prentice served as chairman of the cabinet operations committee and was also a member of the crucial priorities and planning committee.

His resignation removes a recognized "Red Tory" from a governing caucus dominated by the old Reform party wing of the combined Conservative party.

Prentice was a former leadership candidate for the Progressive Conservative party in 2003, which he lost to Peter MacKay.

The native of South Porcupine, Ont., represents a riding in Calgary, where he previously worked as a lawyer specializing in property rights and environmental issues for development projects.

First elected to the House of Commons in 2004, Prentice was named to Harper's first cabinet when the Conservative government took office in 2006.

Prentice was first given the Indian Affairs portfolio, then moved to Industry and most recently to Environment.

He was also chair of the Harper Cabinet's powerful operations committee.

The Harper government has hitched its policy on reducing greenhouse gas emissions to that of Washington, arguing a continental approach is required given the two countries' tight trading relationship.

After this week's U.S. midterm elections in which Republicans took control of the House of Representatives, any expectation of American movement on greenhouse gases regulations has been all but eliminated for the next two years.

That left Prentice in charge of a ministry whose biggest file has effectively been shelved.

Privately, Prentice has been telling people he doesn't expect to be very busy for the next two years.

He may have also wanted to avoid yet another drubbing at an international climate conference.

A United Nations summit in Mexico next month is not expected to yield a successor to the Kyoto Protocol.

Prentice and the rest of the Harper government took a lot of heat at last year's summit in Copenhagen, collecting several 'Fossil of the Day' awards from environmental groups.