You know that EPA Administrator Stephen Johnson is no slouch at rebuffing Congressional inquiries. He's never met a question he couldn't talking-point his way through. And his staff is quite skilled at redaction.

Ever since Johnson made his decision (against the advice of his legal and technical staff) to reject California's petition to pass strict greenhouse gas emission rules for cars and trucks, House sleuth Henry Waxman (D-CA) has been on his case. Back in February, Waxman issued a subpoena to compel the EPA to turn over certain documents. It did. Now he's on the verge of issuing his second subpoena of the investigation (pdf), as he wrote in a letter yesterday to Johnson.

That's because Waxman and his staff have been engaged in prolonged negotiations with the EPA over documents, but patience is wearing thin. The EPA, citing an “Executive Branch confidentiality interest" because the documents "reflect internal deliberations and/or attorney-client communications," has been busily redacting pages. And they also continue to withhold "communications between EPA and the White House and the Department of Justice," Waxman writes -- "hundreds of documents" worth. Johnson has refused to discuss any communications with the White House about the California waiver.

If Johnson doesn't respond with an indication of when Waxman can expect more documents by tomorrow afternoon, he writes, then he'll be forced to consider another subpoena.