Senate Republican Leader Mitch McConnell said Thursday he'll oppose the nomination of John Koskinen as Internal Revenue Service Commissioner.
The Senate is expected to consider the nomination before ending its 2013 session, probably later this week or early next week.
Republicans have been livid about the IRS' targeting of some conservative groups.
"Earlier this year, the Internal Revenue Service admitted responsibility for an incredible abuse of power," McConnell, R-Ky., told the Senate. “In the midst of an election season, it targeted and harassed Americans for the supposed crime of thinking differently.
"An agency with access to some of the most personal information of every taxpaying American betrayed their trust. And in doing so, it showed the lengths to which this administration will go to stifle those who dissent from its policies. All of this was, and remains, an outrage."
He called the IRS' actions "the kind of thing we might expect from a banana republic or a third-world dictatorship, not the world’s leading democracy. And the worst part is, we still don’t know everything that happened — or if it’s still going on."
If confirmed, McConnell said, he expects Koskinen to "provide regular, transparent updates to Congress on the status of implementation, and to let us know of any problems as soon as they arise.
“The last thing we need is for the IRS to compound the pain it and Obamacare have already inflicted upon the American people by allowing fraud and further mistreatment to happen under its watch.
"The IRS has done a lot to lose the trust of the American people. It will need to do a lot more to regain it."