The next day, Attorney General Eric Holder pronounced the agency’s actions “outrageous and unacceptable” and opened an investigation to determine if any laws were broken. But congressional Republicans have voiced dissatisfaction with the Justice Department’s handling of the issue and spearheaded committee probes into the agency’s functions. Issa noted that the House Oversight & Government Reform Committee has conducted 33 witness interviews and five hearings.

Issa added that the IRS has “not fully cooperated” with the committee investigation, leading to the issuance of three subpoenas. Even then, he said, the agency continues to withhold some of Lerner’s emails that bear on the controversy.

Lerner initially was called to appear before the committee on May 22, 2013. At that time she insisted she had not done anything wrong nor had she broken any laws in conducting her duties overseeing tax-exempt groups at the IRS. But she refused further testimony and would not answer committee questions on advice of counsel.

Subsequently, the committee determined that Lerner waived her rights under the Fifth Amendment when she professed her innocence. She was again called before the committee and Issa said she would testify. But she once again refused on advice of counsel. Issa said the panel will consider holding her in contempt.

“As you can see from our questioning today, we have continued to gather facts around Ms. Lerner’s absence of testimony,” Issa told reporters after the hearing. “It would have allowed us to bring this investigation to a — probably pretty quick close if she had been willing to answers those questions. Without it we will undoubtedly have a few more questions to try to find out things that she could have answered quickly today.”

Cummings, who continued to speak in the committee room despite the absence of a microphone, asserted that the committee has gathered sufficient evidence to show that “the White House did not direct this, suggest it, or even know about it at the time it was occurring. And none of the witnesses or the documents identified any political motivation.”

“The Inspector General, Russell George, told us the same thing,” Cummings said. “He found no evidence of any White House involvement or political motivation.  Instead, the very first line of the ‘results’ section of his report says that it began with employees in Cincinnati who ‘developed and used inappropriate criteria to identify applications from organizations with the words Tea Party in their names.’”

The inspector general also determined that Lerner didn’t learn about the use of the 501(c)(4) criteria until 2011 – a year after it was implemented. Once advised, she “immediately directed that the criteria be changed.” Cummings did concede that there was “evidence of gross mismanagement” around Lerner’s role.

The IRS scandal isn’t the only bump in Issa and Cummings’ rocky relationship.

Two weeks ago, Cummings demanded that Issa apologize for suggesting former Secretary of State Hillary Clinton may have told the Pentagon to stand down in the Benghazi attack response. Cummings told the chairman in a letter that his “accusations are beyond the pale, and you should immediately retract them and issue a public apology.”