Grassley, citing a report by the IRS inspector general's office, said political candidates or their donors have been targeted for investigation several times and though the Justice Department has declined to prosecute any of the individuals, they were granted access to tax documents they should not have seen.
Grassley, a Republican, said in one of the four cases, IRS employees willfully turned over documents they knew to be private though the other times it appears the documents were handed over by mistake, The Hill reported Tuesday.
In a letter to Attorney General Eric Holder, Grassley demanded to know why politicians or high-profile donors were targeted for investigation and how the Justice Department handled the cases.
"Although this may not be indicative of widespread targeting, any instance is cause for concern," Grassley wrote to Holder Friday. "Even more alarming, in at least one instance [the inspector general's office] referred evidence of 'willful unauthorized access' to the United States Attorney's Office, but criminal prosecution was declined. Decisions such as these directly impact the political process and should be subject to the scrutiny of the American public."
The IRS revelation comes on the heels of allegations made by Republicans that IRS officials targeted conservative groups seeking tax exempt status, though the authenticity of a report by the same inspector general's office has been called into question, with Democrats charging the report only focused on conservative groups and left out liberal ones that were made to jump through many of the same hoops.
2014: The Year in Music [PHOTOS]