Markey To Billionaire Steyer: Stay Out Of Mass. Senate Race

The Democratic U.S. Senate candidates say environmental activists backed by a California billionaire are running Facebook ads in violation of an agreement that discourages advertising by outside groups in the campaign.

The group Regeneration Mass is criticizing U.S. Rep. Stephen Lynch for supporting the Keystone XL Pipeline, which opponents say will contribute to global warming.

Thomas Steyer of California sent a letter to Lynch this week demanding that he change his position on Keystone by Friday or face negative attacks.

Rep. Edward Markey's campaign manager said in a statement Thursday the ads are a "clear violation" of the so-called "People's Pledge" he and Lynch signed. Under the terms of the agreement, Markey will make a donation to a charity of Lynch's choice.

A spokesman for Steyer says the paid ads do not violate the pledge because they do not mention either candidate.