PASADENA (CBS) — A Southern California congressman said he will voting “no” ahead of a vote that could leave a sitting attorney general held in contempt of Congress for the first time in U.S. history.

READ MORE: Statements From Los Angeles Community College District and California Community Colleges Chancellor’s Office

Democratic Congressman Adam Schiff of Pasadena told KNX 1070 NEWSRADIO he believes the investigation into “Operation Fast And Furious” has turned into a political witch hunt.

“It’s already quite clear that the investigation, which I think began legitimately looking at the facts of ‘Fast and Furious’, has become [untethered] and is now just about going after the President, going after the Attorney General.”

At least four Democrats are expected to cross party lines and vote to hold Attorney General Eric Holder in contempt of Congress for his refusal to turn over some documents related to the Justice Department’s “Fast and Furious” gun-running operation.

If the vote passes the question will become how it might be enforced. This is all about Congress still wanting tens of thousands of pages of documents on the scandal.

The Democrats who have publicly indicated they will vote with Republicans include: Utah’s Rep. Jim Matheson, Georgia’s Rep. John Barrow, West Virginia’s Rep. Nick Rahall, and North Carolina’s Rep. Mike McIntyre.

READ MORE: First Case Of Omicron Variant Detected In LA County

Most people think it’s unlikely they will attempt the criminal route, which would mean Holder’s own staff would have to agree to prosecute him if he doesn’t hand over documents.

There’s another option: Congress can ask a federal court to enforce its subpoena. That’s happened before, a court agreed, and before it could go to appeal the two sides compromised and some documents were exchanged.

Republican Congressman Darrell Issa of Vista said Thursday the White House should not be running interference for Holder.

“Since Nixon, we’ve understood executive privilege does not trump the actual question of, ‘Was Congress lied to or were they covering up a crime?'” said Issa.

There are a few interesting developments surrounding the vote: at least a handful of Democrats are expected to vote with Republicans in favor of contempt. The National Rifle Association is putting on the pressure and some Democrats have a strong gun rights force in their constituency.

Secondly, Democrats say the Congressional Black Caucus is going to lead a walkout during the vote and most Democrats are expected to join.

MORE NEWS: Fake Students Potentially Stealing Millions From Financial Aid

(©2012 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. Wire services contributed to this report.)