Washington ( CNN ) -- Kenneth Melson , acting director of the Bureau of Alcohol , Tobacco , Firearms and Explosives , is expected to resign under pressure , perhaps in the next day or two , in the wake of the controversy over Operation Fast and Furious , two senior federal law enforcement sources said Monday . In the operation , straw buyers were allowed to purchase illegally large numbers of weapons , some of which ended up in the hands of cartels in Mexico . Attorney General Eric Holder will meet Tuesday with Andrew Traver , head of the ATF field office in Chicago , about possibly becoming the agency 's acting director , according to senior federal law enforcement sources , who are familiar with the details of the controversy . The Justice Department refused comment . White House press secretary Jay Carney told reporters he had no new information on the issue . The operation has come under intense criticism since the December killing of a U.S. Border Patrol officer . Operation Fast and Furious was `` a colossal failure of leadership , '' Peter Forcelli , a supervisor at the bureau 's Phoenix field office , said recently . The program focused on following people who legally bought weapons that were then transferred to criminals and destined for Mexico . But instead of intercepting the weapons when they switched hands , Operation Fast and Furious called for ATF agents to let the guns `` walk '' and wait for them to surface in Mexico , according to a report by the House Oversight and Government Reform Committee . The idea was that once the weapons in Mexico were traced back to the straw purchasers , the entire arms smuggling network could be brought down . Instead , the report argues , letting the weapons slip into the wrong hands was a deadly miscalculation that resulted in preventable deaths , including that of Border Patrol Agent Brian Terry . Terry was killed last year north of the Mexican border in Arizona after confronting bandits believed to be preying on illegal immigrants . Two weapons found near the scene of the killing were traced to Fast and Furious . `` I was flabbergasted . I could n't believe it at first , '' Terry 's mother , Josephine , said when she learned the ATF may have let some of the guns used in the attack slip through its fingers . Terry 's relatives said they want all those involved in his killing and who helped put the weapons in their hands to be prosecuted . `` We ask that if a government official made a wrong decision , that they admit their error and take responsibility for his or her actions , '' Robert Heyer , Terry 's cousin and family spokesman , said in a hearing last week by the House panel . The committee 's chairman , Rep. Darrell Issa , R-California , called the operation `` felony stupid . '' As many as 2,000 semiautomatic rifles reached the hands of cartels as a result , and Issa said the top two ATF officials were briefed on the program regularly . In Mexico , the case has drawn nationwide attention and sharp criticism from top officials , who have long stressed that U.S. weapons are fueling the country 's drug war . The Mexican attorney general 's office demanded a quick U.S. investigation of the matter in March and said authorities must hold accountable anyone who was responsible for the operation . `` As the United States government has signaled , the government of Mexico was not informed of any operation that would include the controlled transport of weapons to Mexico , '' the office said .
NEW : Chicago ATF field office head set to meet with attorney general about job , sources say . The sources say the ATF acting director 's resignation could occur in the coming days . The ATF operation allowed illegal gun purchases . Some weapons ended up reportedly in the hands of Mexican cartels .