President Obama announced during a press conference late Wednesday afternoon that he had asked for and received the resignation of Acting IRS Commissioner Steven T. Miller, over the recently revealed news that the agency had been targeting for extra scrutiny the applications of Tea Party and similar groups for tax-exempt status.

“It’s important to institute new leadership that can help restore confidence,” Obama said at the White House.

A report released on Wednesday night by the Treasury Inspector General for Tax Administration revealed that starting as early as 2010, a unit of the IRS had been using a list of politically charged and "inappropriate" criteria to single applications out, including whether the applying group's name included the words "Tea Party," "Patriot" or "9/12." (See "TIGTA: 'Ineffective Management' Led to Targeting.") The watchdog group found no evidence of outside political influence in the singling out of those groups.

Miller, who had been acting commissioner since November 2012, apparently knew about the targeting of the groups as early as May 2012, and has maintained that it was the result of the actions of a small number of IRS employees in a unit in Cincinnati, and not politically motivated.

“This has been an incredibly difficult time for the IRS given the events of the past few days,” Miller wrote in a letter to IRS employees. “And there is a strong and immediate need to restore public trust in the nation’s tax agency.”

No successor was named, and Miller wrote that he would leave the agency in June after working on an “orderly transition” to a new commissioner.

A number of senators and congressman had suggested that Miller resign or be fired, and Attorney General Eric Holder has announced that he will pursue a criminal investigation of the scandal. (See "Holder Orders Criminal Probe of IRS Tea-Party Group Focus.")

 Bloomberg’s Richard Rubin contributed to this report.