A Democratic senator is holding up the nomination of Michael Chertoff (search) as Homeland Security secretary to protest the Justice Department's refusal to provide a secret FBI memo on terror suspect interrogations.

Chertoff is still expected to win Senate approval when lawmakers vote on his nomination Tuesday, but Sen. Carl Levin (search), D-Mich., a member of the Homeland Security and Governmental Affairs Committee, said Thursday he is delaying the inevitable.

"We should make the point during this nomination that we're being denied a document that may relate to the nomination itself," said Levin, who warned that the Justice Department would face a "real bipartisan battle" if it resisted congressional oversight.

The memo -- and the ensuing delay -- is "not necessarily about Chertoff," Levin said. "It may not be, but we may never know."

At issue is a three-page, heavily edited e-mail, marked "Secret" and dated May 10, 2004, that was sent from FBI (search) agents seeking guidance about questioning terror suspects held at Guantanamo Bay, Cuba.

Chertoff, who left the Justice Department in 2003, told lawmakers during his Feb. 2 confirmation hearing that he knew nothing about the memo, who might have written it, or precisely what it discussed. That prompted Levin and Sen. Joe Lieberman, D-Conn., to ask the Justice Department for unedited copies of the e-mail.

In the department's Feb. 7 response, Assistant Attorney General William E. Moschella denied their request, saying the memos contain "information covered by the Privacy Act (search) ... as well as deliberative process material." However, Moschella said, the memo was neither sent nor received by Chertoff, and did not refer to him in any way.

But Levin called the denial an attempt to curb congressional oversight. He was preparing a letter Thursday to Attorney General Alberto Gonzales (search) to demand the letter.

"It is such an extreme, such a radical, such a total unsustainable position by the Justice Department," Levin said. "To say that the Privacy Act denies Congress the right to government documents -- we're talking about government employees, government activity -- to black out their names you can't have any oversight."

A Justice Department spokesman did not have an immediate comment.

Sen. Susan Collins, R-Maine, who chairs the committee, called the delay "very unfortunate."

"The department needs a leader, and every day we delay, we delay the secretary from assuming the position," she said.

Asked if she thought Levin would get the memo, Collins said, "No."

The Senate plans eight hours of debate on the nomination Monday and a vote Tuesday, which would come nearly two weeks after Chertoff's confirmation hearing.