This article suggests that a number of the Democratic signatories have interpretations of "extraordinary circumstances" that include "extreme" ideology or "activism," both of which could be attached to any number of potential Bush nominees. Here are the relevant quotes:

"In my mind, extraordinary circumstances would include not only extraordinary personal behavior but also extraordinary ideological positions," said Sen. Joseph I. Lieberman (D-Conn.), a moderate the White House has been hoping to enlist to give bipartisan backing to the nominee.

Sen. Mary Landrieu (D-La.), one of the 14 who fashioned the agreement, said through a spokesman: "A nominee’s political ideology is only relevant if it has been shown to cloud their interpretation of the law. . . . A pattern of irresponsible judgment, where decisions are based on ideology rather than the law, could potentially be ’extraordinary.’ "

Sen. Ken Salazar (Colo.) rejected Republican assertions that he and other Democratic signers must accept a nominee as conservative as Janice Rogers Brown, now confirmed to a seat on the U.S. Court of Appeals for the District of Columbia Circuit, because the agreement allowed her confirmation. "It didn’t set a standard" for Supreme Court confirmations, Salazar said. "We would leave it up to each person to define what extraordinary circumstance means."

Sen. Ben Nelson (D-Neb.), however, said judicial activism concerns him more than ideology. "Are they going to be an activist?" Nelson asked rhetorically in discussing what might cause him to filibuster a Supreme Court nominee. "Their political philosophy may not bother me at all if they’re not going to be an activist."

That’s four of the seven Democratic compromisers who have signalled that they might abandon the deal. That leaves Robert Byrd, Daniel Inouye, and Mark Pryor as not yet on the record as potential waverers. Has anyone out there read or heard anything about their positions? Can at least three of the seven Republican signatories be counted on to support what seems to be the inevitable need to change the Senate rules? (Which ones? Chafee? Warner? McCain? Snowe? Collins? DeWine? Graham?)

The article also has extended quotations from Karl Rove, including a reference (unlikely merely a misstatement) to "Justice" Gonzalez. (To be clear, I take this as either a trial balloon or mindgames, rather than as a straightforward revelation of the direction of the Bush Administration’s thinking.)

For more, go
here.

Update: Mark Pryor never says never in this article:

A test case of the agreement is whether a nominee as conservative as Janice Rogers Brown, confirmed to the D.C. Circuit Court of Appeals, could get past a filibuster threat for the Supreme Court. Senator Pryor says it’s not clear. "Every nomination is different.... I would hope that Janice Rogers Brown would not ever be considered for the US Supreme Court. But I’d like to reserve judgment on that. I may be wrong about her. She may get on the D.C. circuit and be a wonderful surprise. I may change my mind on her over time. Let her have some time to develop there and show what sort of judge she may be," he said.

There’s also more from Ben Nelson:

"I’m leaving open my judgment as to what ’extraordinary circumstances’ involves," says Sen. Ben Nelson (D) of Nebraska. He says there will be "no surprises," and that members of the Gang of 14 have ongoing discussions on this point.

Stay tuned.