The Internal Revenue Service managed a wide-ranging program that singled out tea party groups for special scrutiny from its headquarters in Washington, D.C., according to bombshell documents released Wednesday by a watchdog organization.

Judicial Watch, a center-right group that specializes in Freedom Of Information Act document requests and lawsuits, said it received a cache of papers from the IRS showing the depth of the Obama administration's involvement in what officials have previously called the work of a few 'rogue agents' in Cincinnati, Ohio.

And letters from U.S. Sen. Carl Levin, a Michigan Democrat, show his involvement in pressing the IRS to target mostly conservative organizations with cumbersome questionnaires seemingly calculated to slow down their applications for tax-exempt status in the middle of an election year.

In one July 2010 email among IRS managers, a lawyer with the Exempt Organizations Technical unit in Washington wrote that his office was 'working the Tea party applications in coordination with Cincy.'

'We are developing a few applications here in DC and providing copies of our development letters with the agent to use as examples in the development of their cases,' wrote government attorney Steven Grodnitzky.

He acknowledged that the flood of tax-exemption applications from tea party groups were considered part of a 'Sensitive Case Report' project, meaning that the IRS 'cannot resolve any of the cases without coordinating with Rob [Choi]' – who was then in charge of IRS 'rulings and agreements' in the agency's Washington, D.C. headquarters.

Tax-exempt status allows social welfare groups to raise money without paying federal income taxes. The privilege is a highly sought-after perk among nonprofit campaign groups, including many that advocate political positions without endorsing candidates directly. Such 'electioneering' is strictly prohibited.

Beginning in early 2010, less than a year before the midterm congressional elections that would see the tea party flex its biggest political muscles, the IRS slow-walked hundreds of the groups' applications for as many as three years, hampering their ability to communicate publicly and advocate positions on issues.

Most liberal groups applying for the same status were swiftly approved, including one application from President Obama's half-brother, whose application was back-dated so he could claim tax advantages retroactively for a foundation he had set up in the name of their common father.

Lois Lerner, who led the IRS's Exempt Organizations division while the scheme was in place, retired in late 2013 – but not before assuring her own agency that no one in her division had developed the criteria that determined which conservative groups were targeted for special scrutiny.

On April 2, 2013, she emailed IRS investigators about a 'Be On the Lookout' (BOLO) list that was circulated agency-wide.

That list, she claimed, 'only contained a brief reference to "Organizations involved with the Tea Party movement".'

She also suggested that government employees in her Cincinnati subagency were not actively looking for ways to 'label cases as "tea party” cases,' but had rules to follow.

'Do the applications specify/state "tea party"?' she said one manager inquired about the proper yardstick to use. 'If not, how do we know [the] applicant is involved with the tea party movement?'

Employees of one 'screening group manager' in Cincinnati, she said, reported that groups with 'Tea Party,' 'Patriots' or ’9/12 Project’ in their names qualified, along with groups that advocated against 'government spending, government debt and taxes,' those that would '[e]ducate the public through advocacy/legislative activities to make America a better place to live,' and those whose case files included statements 'that are critical of the how the country is being run.'

That, however, runs counter to Grodnitzky's claim that managers in Washington, D.C. – not those in Cincinnati – were using test-cases to 'develop' the lengthy set of questions that tea party groups would later characterize as a deluge of harassment.

Some items on multi-page questionnaires demanded the names of volunteers, membership lists, exhaustive archives from Twitter and Facebook, and even the identities of underage recipients of mentoring.

Other emails show that she later asked the U.S. Department of Justice about the possibility of criminally prosecuting tax-exempt groups, notably those on the political right.

Judicial Watch obtained the latest treasure trove of paperwork in an October 2013 lawsuit after the agency refused to turn over the documents four times earlier that year.

'These new documents show that officials in the IRS headquarters were responsible for the illegal delays of Tea Party applications,' Judicial Watch president Tom Fitton said Wednesday in a statement.

'It is disturbing to see Lois Lerner mislead the IRS’ internal investigators about her office’s Tea Party targeting. These documents also confirm the unprecedented pressure from congressional Democrats to go after President Obama’s political opponents.'

'The IRS scandal has now ensnared Congress,' he said.

That claim is a reference to a series of letters from Sen. Carl Levin, a Michigan Democrat who wrote to the IRS in June 2012 to complain about 12 nonprofit groups he wanted investigated for 'political activity.'

Eleven of those organizations are conservative; just one is liberal. The right-leaning groups included the Club for Growth, Americans for Tax Reform, the retiree-focused 60 Plus Association, and the anti-abortion Susan B. Anthony List.

Levin intensified his written complaints as the presidential election approached, sometimes objecting to how the IRS handled 'social welfare' groups and claiming that IRS routinely 'misinterprets the law' by allowing them to engage in any political-related activity while receiving a tax exemption.

Then-IRS Deputy Commissioner Steven Miller replied at one point that the agency has broad discretion – which it appears to have used – in choosing which organizations to approve and which to reject.

'There is no standard questionnaire used to obtain information about political activities,' Miller insisted.

Levin's office did not immediately respond to a request for comment.

In May 2013, a Treasury Department inspector general report found that the IRS had been 'using inappropriate criteria to identify [conservative] organizations applying for tax-exempt status (e.g., lists of past and future donors).'

The IRS's secret program of playing political favorites continued for more than 18 months, the report revealed, and 'delayed processing of targeted groups applications' in the run-up to the 2012 presidential election.

Read more: