CINCINNATI (AP) -- Ohio's Republican U.S. senator is demanding to know if any disciplinary action has been taken against Internal Revenue Service employees at the agency's Cincinnati office for targeting conservative groups and whether they were acting under orders from their supervisors.


Sen. Rob Portman, who has been a vocal critic of the IRS scandal, condemned the IRS on the Senate floor in Washington, D.C., on Thursday and said the only way to begin to repair the public's trust in the agency will be getting to the bottom of what happened.

"We've got lots of questions that need answers," Portman said. "Did the IRS officials act on their own or did they have discretion from their superiors? How high up does the scandal go? What did the White House know and when did they know it?"

Portman also sent a letter to IRS Acting Commissioner Daniel Werfel on Thursday asking him to identify by name and title every employee in the Cincinnati office involved in targeting conservative groups and to explain if and how they've been punished.

And he wants to know whether other employees at the office are under review and who at the IRS is directly responsible for evaluating their involvement.

"Either someone intentionally attempted to use the power of the federal government to target and cripple their political enemies or they lack the competence to oversee a bureaucracy that has grown too big not to fail," Portman said on the Senate floor. "We need an in-depth investigation, one that fully documents the what, the when and the who of the scandal."

Workers at the Cincinnati office have declined multiple requests for comment from their office and homes, most recently Friday.

President Barack Obama's administration has said no senior officials were involved in the decision to give tea party groups extra scrutiny, while some Republicans charge that the targeting was politically motivated.

IRS officials have said the practice was initiated by low-level Cincinnati employees, Portman said, but supervisors would have been involved and someone would have been directing staff. He said investigators will try to learn how high up the supervisory involvement went.

Three congressional committees are investigating the episode and the Justice Department has launched a criminal investigation.

Meanwhile, three top IRS officials in Washington have been replaced over the controversy. Most recently, the IRS official who led the unit that targeted tea party groups was put on paid administrative leave on Thursday, according to congressional officials.

In early 2010, an IRS unit started subjecting conservative groups seeking tax-exempt status to long-lasting, tough reviews, according to a report by a Treasury inspector general.

Portman, a member of the Senate Finance Committee, wrote President Barack Obama a letter last week requesting any written communications from White House and Treasury officials to the IRS about standards for approving tax-exempt organizations, tax compliance for certain tax-exempt nonprofit groups or those organizations' political activity.

A Portman spokeswoman said Friday he hasn't gotten a response to his letter to Obama or to IRS' acting commissioner.

Bonnie Esrig, a recently retired IRS senior manager from the Cincinnati office, has said employees there are being unfairly criticized for trying to keep up with increasing workloads as the number of tax-exempt applications soared in recent years, and that the office was "a nonpolitical environment."

"I'm sure now the vilifying of the IRS and their employees would have a negative impact on morale," she said.