One of Senate Majority Leader Bill Frist's (search) key staffers will resign Friday because of an investigation into how Republicans gained access to Democratic memos concerning opposition to President Bush's judicial nominees.

Manuel Miranda (search), who worked for the Tennessee Republican on judicial nominations, has been on leave since late last month because of the investigation into how Democratic memos stored on a computer server shared by Judiciary Committee members ended up in GOP hands.

But Miranda, a former GOP Judiciary staffer who transferred to Frist's leadership office, offered his resignation and will leave Frist's office as of Friday, Frist spokesman Bob Stevenson said Thursday.

A message left at Miranda's home was not immediately returned. He told The Knoxville News-Sentinel on Thursday he resigned to spare Frist.

"I have departed so as not to distract the majority leader from pursuing the needed legislative agenda for the American people," Miranda told the Tennessee newspaper. "I certainly did not want to burden Senator Frist with matters related to my work on the staff of Senator Orrin Hatch."

He told the same newspaper in January that investigators were looking at work he performed for the Judiciary Committee before he joined Frist's office. "There was no stealing," he said. "No systematic surveillance. I never forwarded these memos — period."

Senate Judiciary Chairman Orrin Hatch (search), R-Utah, began the investigation in November after Sens. Dick Durbin, D-Ill., and Edward Kennedy, D-Mass., protested what they said was the theft of the memos from their servers. The memos, concerning political strategy on blocking confirmation of several of President Bush's judicial nominations, were obtained and reported on by The Wall Street Journal and The Washington Times.

Conservatives have talked up the memos as proof the Democrats colluded with outside liberal groups in their choices of which Bush appellate nominees to block.

Hatch, the Judiciary chairman, also placed an aide on leave late last year for improperly obtaining data from the computer networks of two Democratic senators. That aide, who has not been identified, has since left government work, officials said.

Senate Sergeant-at-Arms William Pickle has been working with the Secret Service and outside investigators since November to try and determine how the Democratic memos got to Republicans. A report is expected to go to Hatch's Judiciary Committee in about two weeks, officials said.

Senate Democratic leader Tom Daschle of South Dakota said he would wait until that report is finished before deciding whether Miranda's resignation will satisfy Democrats. "At that time, we'll be in a better position to make an assessment of not only the investigation, but of the actions taken consequently," Daschle said.