(CBS NEWS) -- President Obama on Wednesday announced that acting IRS commissioner Steve Miller is stepping down amid investigations into political discrimination carried out by the IRS against conservative groups.
Miller, a career bureaucrat at the IRS, was tapped to serve as acting commissioner after commissioner Doug Shulman, who was appointed by President George W. Bush, stepped down in November. Mr. Obama said Miller resigned Wednesday at the request of Treasury Secretary Jack Lew.
A Treasury inspector general report released Tuesday showed that the agency targeted for excessive review conservative groups seeking tax-exempt status.
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"The misconduct that it uncovered is inexcusable," Mr. Obama said, referring to the report. "It's inexcusable and Americans are right to be angry about it. And I am angry about it."
The president said he would "not tolerate this kind of behavior in any agency," but particularly not in the IRS. "As I said earlier, it should not matter what political stripe you're from, the fact of the matter is the IRS has to operate with absolute integrity."
CBS News has confirmed that Miller was informed of the IRS's targeting policy in May 2012. On July 25, 2012, Miller testified before a House Ways and Means Oversight subcommittee, but he did not mention the agency's heightened scrutiny for the applications of conservative groups. After learning of the controversial IRS practice, he also wrote at least two letters to Congress explaining the process for reviewing tax-exempt status applications; in neither of those letters did he mention the targeting.
Attorney General Eric Holder on Wednesday told Congress that the possible criminal violations in the IRS case include "false statement violations" that may have been made.
A timeline released in Tuesday's report showed the IRS in the spring of 2010 began targeting groups with keywords like "Tea Party," "Patriot" and "9/12 Project" in their names to flag for heightened, typically burdensome, scrutiny. The agency insisted last week that no high-level employees were aware of the practice, but the IG report alleges that Lois Lerner - an IRS official in charge of oversight of tax-exempt groups - knew about it as early as June 2011.
A congressional source also tells CBS New that two Cincinnati, Ohio-based employees of the IRS have been disciplined and are "off reservation" in light of the Tuesday report.