Senator Charles Grassley, R-Iowa, today demanded the head of the Justice Department's Criminal Division resign over the controversial ATF gun trafficking program known as Fast and Furious.

Grassley, the top Republican on the Senate Judiciary Committee , said that Assistant Attorney General Lanny Breuer has provided inaccurate statements and information to Congress on Fast and Furious and a Bush-era gun running case called Wide Receiver where the ATF also let guns walk into Mexico.

Under the botched program hundreds of guns flowed into Mexico.  ATF officials say they hoped to track the guns to their ultimate destination, and then make arrests. Instead, many of the guns were used in crimes, including one that was used in the murder of U.S. Border Patrol agent Brian Terry in December 2010.

In recent months ongoing congressional investigations have focused on what senior Justice Department officials knew about the program. Attorney General Eric Holder is set to appear before the House Judiciary Committee on Thursday to testify about the scandal. Last Friday the Justice Department withdrew a February 4, 2011 letter that was sent to Sen. Grassley that asserted that ATF did not let guns walk into Mexico.

Breuer has said that he was not involved in the review or drafting of the letter sent to Grassley's office despite emails showing that he was aware of the initial inquiry from Sen. Grassley and sending drafts of the letter to his personal non-government email account.

"So imagine my surprise when I discover from documents provided Friday night that that Mr.  Breuer was far more informed during the drafting of that letter than he admitted before the Judiciary Committee. In fact, Mr. Breuer got frequent updates on the status of the letter while he was in Mexico." Grassley said on the senate floor.  "If you can't be straight with Congress, you don't need to be running the Criminal Division. It's time to stop spinning and start taking responsibility. I have long said that the highest-ranking official who knew about gunwalking in Operation Fast and Furious needs to be held accountable."

In November Breuer admitted that he made mistakes after being briefed last year about questionable tactics from Wide Receiver for not raising the issue with senior DOJ leadership as prosecutors moved to indict the case in 2010.

"At the time, I thought that - dealing with the leadership of ATF was sufficient and reasonable." Breuer told the Senate Judiciary committee last month when he was asked why he did not raise the issue to DOJ leadership  "And, frankly, given the amount of work I do at the time, I thought that that was the appropriate way of  dealing with it. But I cannot be more clear that knowing now - if I'd known then what I know now, I of course would have told the deputy and the attorney general."

In a statement Justice Department Director of Public Affairs Tracy Schmaler said, "Assistant Attorney General Breuer has acknowledged his mistake in not making - and therefore not alerting Department leadership to - a connection between the allegations made about Operation Fast and Furious and the unacceptable tactics used years earlier in Operation Wide Receiver.  He has acknowledged that mistake to Congress and to the Attorney General, who continues to have confidence in Assistant Attorney General Breuer's ability to lead the Criminal Division."