Anti-Keystone Activists Threaten to Target Mass. Senate Hopeful

Democrat apparently not leftist enough for some

A group of climate-minded activists and a philanthropist have sent a letter to Massachusetts Senate hopeful Stephen Lynch, warning the Democratic congressman that they'll form a super PAC to target him unless he opposes the Keystone pipeline.

The move takes place amid an anti-super PAC pledge signed by both Lynch and the favorite in the Democratic primary, Rep. Ed Markey, to discourage outside groups from airing ads and sending out direct mail.

The letter went out this morning from Tom Steyer, a clean-energy advocate and philanthropist who has poured money into environmental efforts in California, and four other signers.