The head of the IRS has stepped down after a report found that the tax agency was improperly targeting conservative groups.
President Barack Obama says Treasury Secretary Jacob Lew asked for and received Steven Miller's resignation.
Obama said unethical behavior is especially intolerable in the IRS, and safeguards will be put in place to prevent any future political action by the IRS.
"I'll do everything in my power to make sure nothing like this happens again, by holding the responsible parties accountable, by putting in place new checks and new safeguards, and going forward by making sure the law's applied as it should be, in a fair and impartial way," Obama said.
The Treasury Department said the IRS gave extra scrutiny to Tea Party and other conservative groups when they applied for tax exempt status.
The Justice Department has opened a criminal investigation, and the House Ways and Means Committee will hold a hearing Wednesday.