Roll Call offers this report (paid subscription required), which begins: “Senate Majority Leader Bill Frist (R-Tenn.) faces a strong challenge on his right if he brings to the floor a lobbying reform package that cracks down on the independent political groups known as 527s. Sen. George Allen (R-Va.) plans to send a letter to Frist this week threatening to filibuster the bill if it includes the provision, which was approved by the House but is absent from the Senate version of the lobbying rules overhaul. The letter is so far co-signed by GOP Sens. Sam Brownback (Kan.), Tom Coburn (Okla.), Jim DeMint (S.C.), Mike Enzi (Wyo.), John Sununu (N.H.) and David Vitter (La.).”
The letter has been sent, and you can find it here.