President Obama insisted Thursday that he knew nothing about the internal investigation into the IRS' practice of singling out conservative groups for special scrutiny before it was made public, as he moved to name a new director for the embattled agency.

"I can assure you that I certainly did not know anything about the (inspector general) report" beforehand, Obama said Thursday.

The president, though, did not say whether he was previously aware of the IRS' actions, which allegedly started as early as 2010, well before the inspector general's office began to investigate. Republican lawmakers were inquiring about the alleged targeting of Tea Party groups by the IRS more than a year ago.

Obama, who spoke during a press conference alongside the Turkish prime minister, focused his remarks specifically on the IG report, noting that he wouldn't have caught wind of that report since those investigations are typically kept under wraps. He reiterated that he found the agency's actions "unacceptable" and sought to fix the problem "the minute" he found out about it. White House Press Secretary Jay Carney has previously said no one in the White House knew about the practice.

The comments were the latest effort by the White House to tamp down the controversy.

More On This...

After his press conference, Obama announced the appointment of White House budget official Daniel Werfel as the next acting IRS commissioner. This comes after Obama announced Wednesday that acting IRS Commissioner Steven Miller would resign -- though Miller was apparently set to step down anyway.

An official close to Miller told Fox News, shortly after Obama's brief announcement, that the IRS chief was "set to resign the position of acting commission as of early June." He was planning to leave the IRS entirely a "couple of months later, regardless of the current controversy," the source said.

These details were not mentioned by the president as he announced Wednesday evening Miller was resigning. Obama spoke following a meeting with Treasury Secretary Jacob Lew and other top department officials in which they reviewed a highly critical inspector general’s report on the practice. The report concluded poor management allowed agents to improperly target Tea Party and other groups for more than 18 months, starting in 2010.

Obama said Lew asked for the resignation and Miller agreed, after being on the job since November 2012.

“Americans have a right to be angry about it, and I’m angry about it,” Obama said from the White House.

Republicans, who along with Democrats have slammed the IRS for the practice, welcomed the resignation Wednesday but made clear they would continue to investigate and press for accountability.

Rep. Vern Buchanan, R-Fla., said the resignation "is a necessary first step but more heads need to roll."

Rep. Michele Bachmann, R-Minn., reacting to the claim that Miller was leaving anyway, said it seemed like he was a "perfect scapegoat" for the administration.

Miller’s resignation was part of three-step plan Obama outlined to fix the problem.

The other steps are to put in place the safeguards recommended in the IG report and to work with Congress as it investigates.

“The good news is we can fix this,” Obama said.

Miller became acting commissioner after Commissioner Douglas Shulman completed his five-year term. Shulman had been appointed by President George W. Bush.

The president has proceeded cautiously since the IRS controversy was made public Friday. While he initially said the accusations were "outrageous," he also said he wanted to wait until the report was released before addressing what should be done to hold accountable those responsible.

The report lays much of the blame on IRS supervisors in Washington who oversaw a group of specialists in Cincinnati who screened applications for tax-exempt status. It does not indicate that Washington initiated the targeting of conservative groups, but it does say a top supervisor in Washington did not adequately supervise agents in the field even after she learned the agents were acting improperly.

The Justice Department is also investigating the IRS targeting, as are three congressional committees.

Sources told Fox News that Miller will remain on the job "for a couple of weeks."

The House Ways and Means Committee said after the announcement of Miller's resignation that he still will attend a hearing Friday.

And the House Committee on Oversight and Government Affairs sent a letter Wednesday afternoon to the IRS requesting five employees named in the IG audit be made available for transcribed interviews by committee staff.

The Republican-led committee wants to start the interviews Monday.

The names and titles of the IRS employees requested are Holly Paz, a director; John Shafer, a manager; Gary Muthert, a screener; Liz Hofacre, a case coordinator; and Joseph Herr, a manager.

"The resignation of Steven Miller is a positive and important step as this agency struggles to try to regain the public’s trust," said Utah Sen. Orrin Hatch, the top Republican on the Senate Finance Committee. "A clean slate at the IRS with new leadership is imperative to fix this egregious encroachment on the lives of honest, hard-working Americans whose only sin was that they want to express their beliefs."

Earlier in the day, White House Press Secretary Jay Carney sidestepped a question about whether Obama still had confidence in Miller, saying he wouldn't discuss personnel matters. He said Obama has expressed his overall view that IRS personnel had acted inappropriately.

"He wants to see that the actions taken, as revealed by the Treasury report, that are inappropriate, are met with consequences," Carney said. "He will make clear to Treasury Department leaders that he expects action."

Carney said Obama wants the public to "understand and believe that the IRS applies our tax laws in a neutral and fair way to everyone."

The Associated Press contributed to this report.