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Emails among IRS officials, and committee interviews with them, show agency employees were aware of the pressure, sending one another news reports and commenting — in sometimes derisive language — about the tea party applications.

One key question in the political debate has been how the IRS treated progressive groups and whether they received the same treatment as tea party organizations.

The committee report says the liberal groups were generally given quick approval, while some tea party applications are still awaiting approval three years after they were submitted.

“Despite repeated attempts to conflate the issues and downplay the IRS’s treatment of conservative-oriented applications, the facts are clear that the IRS systematically processed conservative-oriented applications in a wholly disparate and unique manner,” the investigators conclude. “The treatment received by Tea Party applicants was unprecedented for tax-exempt applicants engaged in political activity.”

The latest report is particularly detailed in its look at Lois G. Lerner, the former head of the division charged with scrutinizing tax-exempt applications.

Investigators traced a pattern of antipathy toward nonprofit organizations being able to take part in political activity beginning with a 2010 speech at Duke University, where the committee said she was “echoing” Mr. Obama’s criticism of the Supreme Court.

She said the court case “dealt a huge blow, overturning a 100-year-old precedent” — a legal reading that analysts have disputed — and indicated she would like to “fix the problem,” though she said the IRS wasn’t set up to do that.

A day after Ms. Lerner’s Duke speech, a senior IRS official circulated a press release from Sen. Richard J. Durbin, Illinois Democrat, urging the IRS to investigate political spending by Crossroads GPS, a group associated with former George W. Bush political strategist Karl Rove.

Ms. Lerner, who has been removed from that post but remains on the payroll, refused to answer the committee’s questions at a hearing this year, citing her right against self-incrimination.