by Todd Feurer, CBS ChicagoBy CBS 2 Chicago Staff

CHICAGO (CBS) — Illinois House Speaker Michael Madigan has turned down an invitation to testify before a committee investigating possible disciplinary action against him over his ties to the ComEd bribery scandal.

ComEd has been charged with a years-long bribery scheme that sought to influence Madigan, the nation’s longest-serving House Speaker.

Madigan has not been charged with a crime, but in response to the bribery case, Illinois House Republican Leader Jim Durkin and two other GOP lawmakers last month filed a petition requesting the House convene a special investigative committee to look into whether Madigan engaged in “conduct unbecoming a legislator.”

They also submitted a list of witnesses they want the committee to invite to testify before the committee, including Madigan himself, but the speaker sent the committee a letter on Friday informing them he won’t be appearing voluntarily.

“This committee has neither the resources nor the ability to recreate a multi-year federal investigation,” Madigan wrote.

The speaker stressed that his decision not to appear before the committee does not mean he is invoking his Fifth Amendment rights against self-incrimination.

“As I have said before, I have done nothing wrong. I fully believe Leader Durkin’s charge is nothing more than a political stunt motivated by a transparent political agenda using his government office and government resources to earn free media for himself and his political candidates,” Madigan wrote. “The federal investigation is more important than Mr. Durkin’s political theatrics, and I cannot in good conscience take any action that may interfere with a federal investigation or potential prosecutions solely to appease the minority party’s desire to use government resources for a political purpose.”

As part of a deferred prosecution agreement, ComEd admitted attempting to influence legislation regarding the regulatory process that determines the rates it is allowed to charge customers for electricity. ComEd acknowledged it stood to benefit by more than $150 million from that legislation.

Madigan noted the deferred prosecution agreement with ComEd does not accuse him of any crimes or misconduct, but instead accuses ComEd of trying to influence the speaker by providing jobs, contracts, and payments to his associates.

“Let me be clear: that attempt was never made known to me – if it had been, it would have been profoundly unwelcome,” Madigan wrote. “To the extent that anyone at ComEd or Exelon believed that they could influence my conduct as a legislator by deciding to hire someone I may have recommended, someone who worked for me, or someone who did political work for me, they were incredibly mistaken. If they even harbored the thought that they could bribe or influence me, they would have failed miserably. I take offense at any notion otherwise.”

The speaker went on to write that he believes it’s part of his duty as an elected official to help people get jobs, but stressed that he has never promised anyone anything in exchange for hiring someone he recommended.

Madigan also said that Durkin played a pivotal role in passing the legislation ComEd is accused of trying to influence, and should know the measure was the result of years of negotiations by both parties in the Illinois General Assembly.

“If Representative Durkin were to put aside his current political agenda and speak honestly about his experiences with this energy legislation in which he was personally involved, I am certain he would attest that the process of negotiating that bill was bipartisan and his input was likely more valuable than mine,” the speaker wrote.

In a statement, Durkin called on House Democrats and Gov. JB Pritzker to demand answers from Madigan.

“Speaker Madigan continues to take the path that his own House Rules apply to all except him,” Durkin said.

The investigating committee is scheduled to meet Tuesday afternoon in Springfield. According to published reports, ComEd executives have accepted the invitation to testify at the hearing.

In addition to Madigan and ComEd, Republicans on the panel are seeking voluntary testimony from former lobbyist and Madigan adviser Michael McClain, former ComEd CEO Anne Pramaggiore, former ComEd vice president Fidel Marquez, former ComEd lobbyists John Hooker and Jay Doherty, and former Chicago alderman Michael Zalewski.

Doherty, McClain, Zalewski and Pramaggiore also have declined to testify, according to letters provided by the panel’s chairman, Illinois State Rep. Emanuel “Chris” Welch (D-Hillside).