During the summer of 2010, the dozen or so accountants and tax agents of Group 7822 of the Internal Revenue Service office in Cincinnati got a directive from their manager. A growing number of organizations identifying themselves as part of the Tea Party had begun applying for tax exemptions, the manager said, advising the workers to be on the lookout for them and other groups planning to get involved in elections.

The specialists, hunched over laptops on the office’s fourth floor, rarely discussed politics, one former supervisor said. Low-level employees in what many in the I.R.S. consider a backwater, they processed thousands of applications a year, mostly from charities like private schools or hospitals.

For months, the Tea Party cases sat on the desk of a lone specialist, who used “political sounding” criteria — words like “patriots,” “we the people” — as a way to search efficiently through the flood of applications for groups that might not qualify for exemptions, according to the I.R.S. inspector general. “Triage,” the agency’s acting chief described it.

As a grim-faced President Obama denounced the “inexcusable” actions of the I.R.S. last week and lawmakers of both parties lined up in Washington on Friday to accuse it of an array of misconduct, everything seemed so clear: the nation’s tax agency had deliberately targeted conservative activists, violating the public trust — and perhaps the law.