Attorney General Eric Holder takes the hot seat today in what is expected to a contentious hearing over the botched ATF gun running operation "Fast and Furious" before the House Oversight and Government Reform Committee. 

The committee has been investigating the actions by ATF and Justice Department officials into the gun trafficking case that resulted in about 2,000 guns being allowed to go to drug cartels and criminal groups in Mexico. The ATF operation took a tragic toll when two guns linked to the operation were found near slain U.S. Border Patrol agent Brian Terry on Dec. 14, 2010.

On Tuesday, the committee's chairman, Rep. Darrell Issa, R-Calif., threatened to hold Holder in contempt of Congress, claiming that the Justice Department has been withholding documents related to the congressional inquiry into Fast and Furious.

"If the department continues to obstruct the congressional inquiry by not providing documents and information, this committee will have no alternative but to move forward with proceedings to hold you in contempt of Congress," Issa wrote to Holder.

Issa also addressed concerns he had over the head of the Justice Department's Criminal Division, Lanny Breuer, proposing a cross-border operation with Mexican law enforcement officials to make arrests of gun straw purchasers on the border.

In the letter to Holder, Issa alleged a cover-up, suggesting Justice Department stonewalling.

"Since the Department initially misrepresented the facts and misled Congress, it is necessary to investigate the Department's response to our investigation," he wrote. "Your actions lead us to conclude that the Department is actively engaged in a cover-up."

Issa is giving the Justice Department until Feb. 9 to turn over the requested documents.

On Wednesday, the Justice Department responded with Deputy Attorney General Jim Cole writing to Issa. 

"Your criticisms of the Department, in general, and Assitant Attorney General for the Criminal Division Lanny Breuer, in particular, seem predicated on significant misunderstandings … of the documents we recently produced," Cole wrote.

Cole also defended Breuer, noting, "It is inconceivable that his intention was to have guns released into Mexico."

Cole wrote that the Justice Department has cooperated with Issa's investigation and has provided numerous resources, telling the committee that the department has provided more than 6,400 pages of material, made numerous witnesses available to testify, and had a team of lawyers collecting and reviewing requests and documents for the investigation.

In prepared testimony,  Holder is expected to repeat many of the same points he has made before and to emphasize reforms at the ATF.

"If some of my comments today sound familiar, it is because this marks the sixth time I have answered questions about this operation before a congressional committee in the last year," Holder's prepared testimony reads.

Holder also is expected to repeat "something that cannot be said often enough: Allowing guns to 'walk' - whether in this administration or in the prior one - is wholly unacceptable."

The Justice Department's inspector general is also conducting an internal review of the ATF and Justice Department's activities in the Fast and Furious operation and is also looking at cases from the Bush administration where guns were allowed to cross the border into Mexico in 2006 during what was known as Operation Wide Receiver. Both Wide Receiver and Fast and Furious were  run by the ATF's field office inn Phoenix.

Last year, ATF agents who acted as whistleblowers from the Phoenix field office and their supervisor, William Newell, testified before Issa's committee.

Holder and top officials have been grilled by Congress over an inaccurate part of a letter sent to Congress about Fast and Furious.  Assistant Attorney General Ronald Weich wrote in the Feb. 4, 2011, letter to Sen. Charles Grassley, R-Iowa, "ATF makes every effort to interdict weapons that have been purchased illegally and prevent their transportation to Mexico."

The Justice Department formally withdrew the letter late last year because of the statement and released a series of internal documents showing how the letter was crafted with input from officials at the U.S. attorney's office in Arizona and ATF officials.

Issa and Holder butted heads at a hearing on the controversy last December before the House Judiciary Committee, with Issa calling Holder a "hostile witness" and comparing him to Nixon Attorney General John Mitchell, who was sent to prison for his involvement in Watergate.