J. Russell George, Treasury Inspector General for Tax Administration, testifies on Capitol Hill, May 21, 2013, before the Senate Finance Committee hearing on the IRS practice of targeting applicants for tax-exempt status based on political leanings. (Charles Dharapak/AP)

Two House Democrats on Thursday called for an investigation of a federal auditor who accused the Internal Revenue Service of gross mismanagement and targeting advocacy groups for extra scrutiny based on their names and policy positions.

Reps. Gerald E. Connolly (D-Va.) and Matthew Cartwright (D-Pa.) on Wednesday filed a complaint with a special watchdog council questioning the independence of Treasury Department inspector general J. Russell George, who is a member of the council.

The congressmen, both top Democrats on House oversight committees, said George produced a “fundamentally flawed performance audit” that was “incomplete” and “outright misleading.” They also alleged that he held briefings with Republican members of the House oversight committee without the knowledge of Democrats on the panel.

George on Thursday stood behind the findings of his review but declined to comment about the meeting allegations.

Karen Kraushaar, a spokeswoman for the inspector general’s office, defended the inspector general’s audit Thursday, saying it “looked at the entire process of how the IRS was reviewing 501(c)(4)s,” otherwise known as social welfare groups.

George added: “We noted there were other ‘be on the lookout’ lists that included other types of organizations, but that was not the initial charge of the review and not the focus.”

The inspector general’s report, released in May, said the IRS “used inappropriate criteria that identified for review Tea Party and other organizations applying for tax-exempt status.” Earlier that month, then-IRS official Lois Lerner alluded to the findings when she acknowledged in response to a planted question that the agency had targeted groups with “tea party” and “patriot” in their names.

The complaint against George follows a letter that Rep. Elijah E. Cummings (D-Md.) and Connolly sent to George suggesting that he had narrowed the scope of his IRS review after agreeing to hold one-party meetings with Republican staff on the House oversight committee, headed by Rep. Darrell Issa (R-Calif.). Cummings is the ranking Democrat on the panel, while Connolly is the top Democrat on one of its subcommittees.

The letter asked George to hand over documents from his office that related to defining the audit’s limits. It also asked the inspector general to avoid meetings that would exclude Democrats and to provide Democratic staff with the briefings they missed.

Critics of the IRS report say the audit focused too much on an a “be on the lookout” list that targeted groups with conservative names, while ignoring older lists that contained terms associated with progressive themes. Republicans have used the report to attack the Obama administration but have failed in their efforts to link the problems to White House political motives.

George’s audit led to public outrage, six federal investigations and a leadership shake-up at the IRS. It also prompted the Treasury Department to draft potential new guidelines to distinguish what types of activities could disqualify groups from tax-exempt status, defining certain election-related initiatives, such as preparing voter guides or holding voter-registration drives, as “candidate-related political activities.”

Supporters of the recommended rule changes say they would set clearer boundaries and help IRS employees understand which applications to reject. But many Republicans and others have opposed the recommendations, saying they could hinder free speech.

Connolly and Cartwright sent their complaint to three members of the Council of the Inspectors General on Integrity and Efficiency on Thursday. The recipients were: Joseph Campbell, a top official with the FBI’s criminal investigation division; Beth Colbert, deputy director of management for the White House Office of Management and Budget; and Phyllis K. Fong, the Department of Agriculture inspector general.