A long-awaited report on a botched effort to control gun smuggling along the U.S.-Mexico border is expected to be released on Wednesday after a 19-month review by the U.S. Justice Department’s internal watchdog.

The report from the department’s inspector general will address Operation Fast and Furious, in which U.S. agents tried to dismantle smuggling rings that fed weapons to drug cartels.

By overlooking low-level suspects, the agents in effect allowed 2,000 firearms to cross the border, critics say.

The operation is a focal point for Republican attacks on Attorney General Eric Holder, the chief U.S. law enforcement official and an appointee of President Barack Obama. The Republican-led House of Representatives voted in June to find Holder in contempt for withholding documents on the matter.

Gun owners, an important Republican constituency in swing states such as Pennsylvania, are especially energized by the scandal. Many believe it is part of an effort by the Obama administration to curtail gun rights.