* Administration officials knew of audit findings as early as last month
* Congress to quiz top U.S. tax agency and Obama officials
* Pressure builds as IRS officials to appear at hearings (Recasts, changes throughout)
Two senior White House aides knew weeks ago that a probe of the Internal Revenue Service had found that the U.S. tax agency had inappropriately targeted conservative groups, but did not tell President Barack Obama, a White House spokesman said on Monday.
A Treasury Department official informed White House counsel Kathryn Ruemmler on April 24 about the preliminary findings of a report that would fuel the latest in a series of scandals to confront Obama at the start of his second term.
The report was issued by a Treasury inspector general on May 14, four days after an IRS official had acknowledged, and apologized for, the agency's targeting of conservative groups with names such as "Tea Party" and "Patriots" that had applied for tax-exempt status.
Soon after learning of the report's preliminary findings, Ruemmler briefed White House Chief of Staff Denis McDonough and some other senior staff members, White House spokesman Jay Carney told a regular news briefing.
Ruemmler chose not to inform Obama about the findings to avoid any appearance that he had any role in shaping the report - a role the president would not have taken anyway, Carney said.
As a result, said Carney, Obama did not learn of the findings until they were announced last week - as the president has himself stated.
Monday's disclosures revealed more about the inner workings of the White House than they did about the IRS scandal, which revolves around questions such as who imposed the inappropriate targeting by IRS employees in the agency's office in Cincinnati, Ohio, and whether IRS officials misled Congress last year about whether they knew that targeting was going on.
Answers to such questions could begin to emerge during congressional hearings scheduled for Tuesday and Wednesday, in the Senate Finance Committee and House of Representatives Oversight and Government Reform Committees, at which IRS and Treasury officials are scheduled to testify.
Such hearings have become an increasingly familiar scene on Capitol Hill, where Republicans are also investigating the Obama administration's response to the deadly attacks on the U.S. mission in Benghazi, Libya, last September.
Lawmakers in both parties are also questioning moves by Obama's Justice Department to suppress leaks to the news media on grounds of national security, namely its seizure of some phone records of journalists from the Associated Press.
The IRS case has also provoked bipartisan outrage.
Democrats have blamed IRS bungling for the scandal, while some leading Republicans, including Senate Minority Leader Mitch McConnell, have questioned whether the administration abused its power in targeting conservative groups.
The inspector general's report said it had found no evidence that officials above the IRS had directed the targeting, or any sign of political motivation by still-unidentified agency employees.
On Monday, Carney reiterated that the White House had not tried to influence the report, or conceal any knowledge of targeting of conservative groups before last November's presidential election.
"No one in this building intervened in an ongoing independent investigation, or did anything that could be seen as intervening in that investigation," Carney said.
In elaborating as to why there was no urgency to tell Obama about the probe's findings, Carney noted that the targeting by IRS agents had been stopped last year.
Last week, Carney played down what Ruemmler knew about the report's findings. But on Monday, he gave a more detailed account, saying Ruemmler was told on April 24 that the report would address "line IRS employees improperly scrutinizing ... organizations by using words such as Tea Party and Patriot."
Carney said that "while we had an indication of the likely findings, until the IG finalizes his report, the findings and conclusions are subject to change. That's why we had to wait, appropriately, until the report was publicized or published for the president to be able to review it and respond."
In that response on Wednesday, Obama called the inspector general's findings "outrageous" and fired acting IRS Commissioner Steven Miller.
Republicans on Capitol Hill were not impressed with the White House's revelations on Monday.
"The White House still can't get its story straight," said Brendan Buck, a spokesman for House of Representatives Speaker John Boehner.
"Today's admission that senior White House officials were told about the IRS targeting, despite repeated suggestions to the contrary over the past week, is more evidence that this scandal requires a full investigation," Buck said.
Some lawmakers have been calling for the Obama administration to fire more people linked to the scandal.
Lois Lerner, chief of the IRS tax-exempt unit, is scheduled to testify on Wednesday to the House oversight committee, along with other officials. It was Lerner's apology on May 10 for the IRS targeting at a legal conference in Washington set off the current furor.
Democratic Representative Sander Levin called for Lerner's resignation on Friday, saying that she had recently testified to a House subcommittee and failed to disclose what she knew.
"This is wholly unacceptable," said Levin, the top Democrat on the House Ways and Means Committee, which writes tax law and oversees the IRS.
Republican Vern Buchanan, another member of the Ways and Means panel, has also called for Lerner to be dismissed.
So far the scandal has claimed two IRS officials: Miller and Joseph Grant, acting commissioner for the IRS tax-exempt and government entities division and Lerner's boss. Grant said last week that he will retire.
TWO HEARINGS AHEAD
Lerner is scheduled to testify on Wednesday to the oversight panel alongside Deputy Treasury Secretary Neal Wolin, former IRS Commissioner Douglas Shulman and Treasury Department Inspector General for Tax Administration J. Russell George.
On Tuesday, George, Miller and Shulman are scheduled to testify before the Democrat-controlled Senate Finance panel.
As the IRS scandal has widened, Republicans have focused on what officials knew about the targeting and when they knew it.
The inspector general's report showed that the targeting of conservative groups began in mid-2010. It said that in 2011, Lerner was told how a Cincinnati field office had carried out such targeting. She halted the use of the controversial key words, but by January 2012 lower-level employees had started using them again, the report said.
On Monday, Max Baucus, the Democratic chairman of the Senate Finance Committee, and the top Republican on the committee, Orrin Hatch, requested documents on possible White House involvement and sought records of nearly 300 applications for tax-exempt status that were delayed by the targeting.
Baucus and Hatch also asked for evidence of any disciplinary action taken, and whether some lawmakers' calls for the IRS to crack down on tax-exempt groups played any role.