House lawmakers plan to press top Veterans Affairs officials this week to explain why, after a series of scandals, they have had limited success holding employees accountable for misconduct.

At a hearing Wednesday, the Committee on Veterans’ Affairs says it will examine VA’s “continued and pervasive lack of accountability” for employees who deceived taxpayers and veterans by covering up long waiting times for treatment at 100 medical centers.

Across the system, just three low-level employees have been fired after the scandal, which unfolded last year in Phoenix, with no firings of senior executives who were involved. Committee aides also say that no employees in Phoenix have been successfully disciplined for their roles, while several remain in limbo on paid leave.

But lawmakers in both parties have broader concerns about VA’s slow progress punishing poor performers and holding employees involved in misconduct accountable, a fault line Secretary Robert McDonald pledged to correct when he took over the agency last year.

Lawmakers are expected to press Deputy Secretary Sloan Gibson on Wednesday on the case of two senior executives who were demoted in November in response to allegations that they manipulated VA’s hiring system for their own gain.

Diana Rubens and Kimberly Graves were demoted from senior executives, the highest rank for career employees, one rank down to GS 15 on the General Schedule.

VA’s deputy inspector general found in a report this fall that Rubens and Graves forced lower-ranking regional managers to accept job transfers against their will. The women then took the vacant positions themselves, keeping their pay but reducing their responsibility.

Committee Chairman Jeff Miller (R-Fla.), joined by the American Legion, criticized the demotions as inadequate punishment and said Rubens and Graves should have been fired. The women also face possible criminal prosecution. They had received more than $400,000 in questionable moving expenses through a relocation program for VA executives, the watchdog found. Miller has criticized VA officials for not recouping the money.

The other federal agencies, VA is struggling with a personnel system that makes firing and disciplining problem employees a cumbersome and costly process that is not always successful.

The House last summer passed a controversial bill that would give the government more power to fire poor performers at VA; the bill has not passed the Senate.

McDonald has been under pressure to show he is doing more to hold wrongdoers accountable. He has publicly given conflicting numbers of employees his staff has disciplined and fired since he has been in charge. The committee is likely to press Gibson on the secretary’s varying accounts.

VA has settled dozens of cases with whistleblowers who report wrongdoing, particularly those who revealed the patient wait-times scandal. But there has been little accountability for managers who retaliated against the whistleblowers, according to advocates and lawmakers.

U.S. special counsel Carolyn Lerner wrote to President Obama about this issue in September, noting the disparity in punishments for whistleblowers and those who retaliate against them.