(CNN) -- In an exclusive interview Sunday on CNN's "State of the Union" with Candy Crowley, Republican Rep. Darrell Issa said interviews with workers in the Cincinnati IRS office show targeting of conservative groups was "a problem that was coordinated in all likelihood right out of Washington headquarters - and we're getting to proving it."

"My gut tells me that too many people knew this wrongdoing was going on before the election, and at least by some sort of convenient, benign neglect, allowed it to go on through the election," he said. "I'm not making any allegations as to motive, that they set out to do it, but certainly people knew it was happening."

A bipartisan group of investigators from two House committees -- Ways and Means, and Government Reform and Oversight -- interviewed two front-line employees from the tax-exempt office last week.

One of the employees hit back against accusations that lower-level employees were responsible for the scrutiny of conservative groups seeking tax-exempt status in 2010, telling congressional investigators that the Ohio employees were being "thrown underneath the bus."

A second "more senior" Cincinnati IRS employee said they began seeking other jobs when they were assigned to look out for applications from tea party groups, because they felt it was inappropriate.

According to excerpts released by the oversight committee, one of the employees said their supervisor told them the direction to single out conservative groups came from the Washington headquarters in March 2010.

By April, seven hard-copy versions of applications had been sent to Washington, the employee said. In addition, the employee said Washington had requested part of an application by two specific groups, though the excerpts do not disclose the names of those two groups.

Shortly after news of the scandal broke and IRS Commissioner Steven Miller announced his resignation, the IRS said two "rogue" employees in the agency's Cincinnati office were principally responsible for the "overly aggressive" handling of requests by groups with the words "tea party" and "patriot" in their names, a congressional source told CNN.

Issa's committee released only excerpts and not the full transcripts of the interviews, citing the fact that the investigation is ongoing. CNN asked for the full transcripts, but the committee did not agree to the request. CNN has not seen the full transcripts or the context of the questions and answers.

However, Rep. Elijah Cummings, ranking member on the House oversight committee, described Issa's remarks based on the interviews as "reckless" and "unsubstantiated."

"So far, no witnesses who have appeared before the Committee have identified any IRS official in Washington DC who directed employees in Cincinnati to use 'tea party' or similar terms to screen applicants for extra scrutiny," Cummings said in a statement.

"Chairman Issa's reckless statements today are inconsistent with the findings of the Inspector General, who spent more than a year conducting his investigation," he continued.

"Rather than lobbing unsubstantiated conclusions on national television for political reasons, we need to work in a bipartisan way to follow the facts where they lead and ensure that the IG's recommendations are fully implemented."

Issa said the full transcripts would be made public, and he has also subpoenaed the administration for more documents that he says will support claims made in the employee interviews. "As we get those documents ... we will learn the whole truth," he said. The oversight committee later clarified that subpoenas have not been issued to the IRS.

For now, however, he has not said he has evidence to verify there was a direct link between Washington and the over-scrutinizing of tea party groups. But he points to the interview, in which one of the employees named an IRS attorney in Washington, D.C. (the name was redacted in the excerpts), who was heavily involved in the process of applying further scrutiny to conservative groups. The employee expressed frustration with the attorney's "micromanagement," according to the excerpts.

Citing the decision by IRS tax exempt director Lois Lerner to plead the Fifth in her recent congressional hearing appearance, Issa said "This is a problem that's coordinated in all likelihood right out of Washington headquarters, and we're getting to proving it. We have 18 more transcribed interviews."

As the IRS began to disclose information about its admitted mistake, Lerner told reporters that the Cincinnati office, which handles the tax-exempt applications, was overwhelmed with applications in 2010 and began funneling documents from conservative groups into a file that called for further review as a "shortcut," chalking it up to more of a clerical error.

"It was an error in judgment and it wasn't appropriate," Lerner said May 10 on a conference call with reporters. "But that's what they did."

When pressed by reporters, White House Press Secretary Jay Carney reiterated the IRS statement that the activity came from line employees in the Cincinnati office.

Asked by the congressional investigators about the allegations, one employee said, "It's impossible."

"As an agent we are controlled by many, many people. We have to submit many, many reports. So the chance of two agents being rogue and doing things like that could never happen," the employee said.

Further pressed to give a reaction to reports that the blame lies within the Cincinnati office, the employee said: "Well, it's hard to answer the question, because in my mind I still hear people saying we were low-level employees, so we were lower than dirt, according to people in D.C. So, take it for what it is."

The employee maintained that the office was following directions from Washington. Asked again if the directions to single out tea party applications specifically came from Washington, the employee gave a less certain answer, saying, "I believe so."

The "more senior" employee told the investigators they were searching for another job in July 2010 after feeling uncomfortable with the task.

"The subject area was extremely sensitive and it was something that I didn't want to be associated with," the employee said.

Ultimately, Issa said, the employees shouldn't get a pass.

"Ethically, they clearly knew this was wrong. They should have become whistle-blowers. They should have done something on behalf of the American people," he said.

The IRS has told House GOP investigators it has identified 88 IRS employees who may have documents relevant to the congressional investigation into targeting of conservative groups.

The agency has so far missed two deadlines to provide documents requested by Congress, but said in a statement Friday that the new acting commissioner, Danny Werfel, is "moving aggressively and taking the data requests very seriously."

"As a precautionary measure, the IRS is casting a wide net to capture any potentially related materials. Our goal is to be exceedingly thorough during this process to ensure we identify any and all pertinent records," the IRS statement said. "The IRS has received numerous congressional requests involving an extensive set of questions and calls for data. Responding to these requests is a top priority for us. We have been in contact with committee staff, and we continue to provide them updates as we diligently work through these requests."

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