A legislative panel investigating House Speaker Michael Madigan reconvenes Tuesday on the same day a former top Commonwealth Edison official is expected to plead guilty to federal charges tied to the utility’s bribery-stained lobbying efforts targeting the speaker.

The House committee probing potential misconduct by Madigan could hear Tuesday from a top Exelon official and former federal prosecutor who was hired to repair the utility’s damaged reputation following its July acknowledgment of a 9-year illegal effort to woo Madigan.

But perhaps the bigger headline could emerge at a noon hearing at the Dirksen Federal Building, where Fidel Marquez, ComEd’s former in-house lobbyist, is expected to enter a plea to a charge that he engaged in a conspiracy to commit bribery to help the utility advance its Springfield wishlist.

“We’ll be watching the Marquez court appearance closely to see if there is any additional information that comes out of that,” said State Rep. Tom Demmer, R-Dixon, who serves as the top Republican on the bipartisan committee investigating Madigan.

Earlier this month, federal prosecutors filed what’s referred to as a criminal information sheet against Marquez, which typically signals a defendant will be pleading guilty and possibly cooperating with federal prosecutors.

In that filing, Marquez, former chairman of ComEd’s political-action committee, was charged with offering no-work jobs and contracts to Madigan associates and directing more than $37,000 in cash payments through a company that then disbursed those funds to Madigan allies.

No other former ComEd executives or lobbyists face criminal charges so far.

Demmer said Marquez has not declined the committee’s invitation to provide testimony to the legislative committee, like ComEd’s former CEO and lobbyists have done.

Former federal prosecutor David Glockner, who is now ComEd’s executive vice president for compliance and audit, is expected to be on-hand to testify Tuesday. As of now, Glockner is the only witness who has committed to appearing before the House panel.

Late Friday, Madigan and several other figures referenced in the federal corruption investigation rejected invitations to appear before the panel.

Madigan released a three-page letter, denying that he engaged in any wrongdoing and declining to testify because he could not “in good conscience take any action that may in any way interfere with a federal investigation.” The speaker did not explain how answering questions under oath about his involvement with ComEd might do that.

Demmer said the committee should consider using its subpoena power to compel Madigan and other witnesses to appear.

“That’s precisely why we need to hear from him as a committee,” Demmer said. “That letter shows that he does indeed have things to say to the committee, and I think it would be appropriate that those were done in-person rather than just through a one-way letter.”

In a sign of the political animosity underlying the entire process, House Minority Leader Jim Durkin, R-Western Springs, who helped initiate the legislative probe into Madigan, had wanted to present an opening statement to the committee, but the panel’s chairman, Rep. Emanuel “Chris” Welch, D-Hillside, ruled out that possibility Monday.

Welch said House rules don’t permit Durkin to participate in the hearings in the manner he wants, but added the House GOP leader may be called as a witness “due to his significant involvement in the energy legislation referenced in his petition.”

Durkin retorted with a statement of his own, asserting that Welch is “not well-versed on the proceedings,” and contended that he will be making an opening statement and asking questions of ComEd.

“See you there!” Durkin concluded.

Editor’s note: In the interest of full disclosure, ComEd is a WBEZ underwriter.

Dave McKinney and Tony Arnold cover Illinois politics for WBEZ. Follow them @davemckinney and @tonyjarnold.