A group of big right-wing activists wrote an open letter to House and Senate Republicans, telling them they are “entering into a period of testing,” wherein their conservative principles will be challenged and “the whole leftist apparatus is gearing up to panic you and to force you to cave in. Don’t do it.”

The letter, posted by conservative columnist Morton Blackwell onRedState.com, urges lawmakers to be strong against the liberals’ “current power grabs.”

“If Republicans cave in now, when it really counts, next time you will be weaker, because your conservative base will be outraged,” the letter says. “Many who worked hard to elect you in the past will never lift a finger for you again.”

Blackwell is president of The Leadership Institute, the group thathelped launch James O’Keefe’s career. And he’s in good company: The list of signatories reads like a who’s who of right-wing activism. For starters you’ve got Colin Hanna of the Tea Party group Let Freedom Ring, Phyllis Schlafly, president of the Eagle Forum, and Erick Erickson, CNN contributor and RedState’s most well-known blogger.