Republicans don't trust the Justice Department to investigate the Internal Revenue Service targeting of conservative groups and now want the department's inspector general to look into the matter instead.

Rep. Frank Wolf, R-Va., a top appropriator who oversees spending at the Justice Department, sent a letter to department Inspector General Michael Horowitz on Thursday calling on him to “investigate the actions taken to date” by the Justice Department to look into the targeting scandal.

The department’s probe of the IRS actions began in May 2013.

“More than one year later, there are no indications that a serious investigation is underway,” Wolf wrote.

Republicans have long expressed doubts about the Justice Department probe of the matter, with many calling for an investigation by an independent prosecutor.

In January, lawmakers were told that Attorney General Eric Holder had assigned a top Obama donor to handle the case for the Justice Department, angering many Republicans.

Justice Department lawyer Barbara Bosserman has donated $6,750 to Democrats and to Obama in the past decade.

“Justice has refused to reassign the case — despite her political conflict of interest — and Ms. Bosserman has so far turned up nothing.”

Wolf signed the email then added a note in blue ink to Horowitz:

“This is important. Thank you.”