Operation Fast and Furious, the controversial gun-tracking effort that has prompted calls for some heads to roll at the Department of Justice, is having another side-effect: delaying a Senate vote on Kathryn Keneally, who has been nominated to be Assistant Attorney General to head DOJ’s Tax Division.

Sen. Charles E. Grassley of Iowa, the ranking Republican on the Senate Judiciary Committee, says Keneally seems qualified and that he’s prepared to vote for her. “However, given the lack of cooperation I’m getting from the Department of Justice, I can’t commit to moving forward with her nomination on the Senate floor,” Grassley said last week as the furor over Fast and Furious seemed to peak.

Grassley has been among the loudest critics of Fast and Furious, in which the Bureau of Alcohol, Tobacco, Firearms and Explosives allowed straw buyers to acquire hundreds of guns so that they could be tracked across the U.S.-Mexican border, helping law enforcement root out Mexican gangsters. The endeavor backfired mightily, as the ATF lost track of many of the weapons, two of which were found at the scene of a shootout a year ago in which a Border Patrol agent was killed.

Grassley has zeroed in on Assistant Attorney General Lanny A. Breuer, accusing the Criminal Division chief not only of  “incredibly poor judgment” but of being intentionally misleading in his statements about Fast and Furious. Grassley demanded last week that Breuer step down, or be fired by Attorney General Eric Holder (see Main Justice’s report).

Grassley has demanded that DOJ officials who are interviewed in the inquiry over Fast and Furious not double-team their questioners by being accompanied by both DOJ and personal lawyers.  Until the DOJ cooperates, Keneally’s nomination may languish, even though Grassley said she demonstrated an impressive command of tax issues — impressive, at least, when compared to those of Mary Smith, whose nomination to head the Tax Division was withdrawn after her critics complained her main qualification was not expertise in tax matters but her political connections (see Main Justice’s report).

The Fast and Furious controversy could also stall the nomination of Kevin A. Ohlson, a high DOJ official and longtime aide to Holder, to the U.S. Court of Appeals for the Armed Forces, as Main Justice noted recently.