The U.S Chamber of Commerce is the world’s largest not-for-profit commercial federation, representing some 3 million businesses. But it no longer represents Apple Inc. AAPL .

On Monday, Apple resigned from the Chamber “effective immediately” over the organization’s opposition to the Obama administration’s environmental policies.

“We strongly object to the Chamber’s recent comments opposing the EPA’s effort to limit greenhouse gases,” wrote Apple government affairs vice-president Catherine Novelli to Tom Donohue, CEO of the Chamber of Commerce. “Apple supports regulating greenhouse gas emissions, and it is frustrating to find the Chamber at odds with us in this effort.” (link)

The move follows similar — if not quite so harshly framed — moves by Nike NKE , Pacific Gas & Electric, PNM Resources PNM and Exelon EXC .

In recent weeks, Apple has made a concerted effort to reposition itself as environmental leader. Steve Jobs even gave BusinessWeek a rare interview to push his green agenda.