Continuing the conservative rebellion against Senate GOP leaders, four Republican-appointed members of the U.S. Commission on Civil Rights urged Majority Leader Bill Frist (Tenn.) to spare a top aide from any punishment related to the investigation into Judiciary Committee memos.

In a letter to Frist, the quartet wrote that Frist’s top aide on judicial nominations, Manuel Miranda, is “man of great professional integrity” and “committed to the highest moral and ethical standards.”

Led by Abigail Thernstrom, a UCCR member and longtime activist in conservative circles, the commissioners have become the latest group of conservatives to lash out at Frist in support of Miranda. The staffer has been placed on leave pending the results of the investigation into Democratic committee memos that ended up in several media outlets. Even Rush Limbaugh spent a portion of his Thursday broadcast attacking Senate leaders, saying Frist was allowing Senate Democrats to distract the issue of how liberal interest groups push them on nominations.

“This is war, this is politics, and we’ve got dirt on the Democrats, and guess what? Republican Senators are siding with Ted Kennedy [D-Mass.] and not fighting this,” Limbaugh said.

The investigation began after memos from Kennedy and another senior Democrat on Judiciary, Sen. Dick Durbin (Ill.), ended up in a Wall Street Journal editorial.

Sergeant-at-Arms Bill Pickle has been conducting an investigation into the memos since mid-November, and last week his investigators focused part of their probe on how the memos ended up in the media — apparently meeting with little success. The Wall Street Journal’s editorial board announced in an editorial Thursday that it had been contacted by Pickle’s investigators, whose questions focused on Miranda, and the newspaper told them to “take a hike.”

The investigators also late last week contacted the Committee for Justice, a conservative group formed in 2002 to fight for President Bush’s nominees and push the issue in the media. While sources indicated the Sergeant-at-Arms officers got nowhere, aides at the committee declined to comment.

As the investigation has circled closer and closer to Miranda, Democrats have grown publicly quiet about the probe but have privately been warning of serious consequences if he retains his job.

This has created a two-front fight for Frist and Judiciary Chairman Orrin Hatch (R-Utah), who is also under pressure from conservatives to not punish Miranda. Another junior staffer has already admitted to taking the documents from a server jointly shared by Democrats and Republicans, and left the Judiciary Committee a month ago. Hatch has said that staffer denies giving the memos to the media.

Thernstrom and the other commissioners — Peter Kirsanow, Jennifer Braceras and Russell Redenbaugh — asked Frist to spare Miranda. “We are shocked and saddened by the media onslaught and hope that this matter can be resolved promptly and fairly,” the commissioners wrote in a letter sent Friday.